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Medical Devices / Diagnostics

How do ultrasound scans work?



An ultrasonic scan uses sound waves of high frequency to produce images of the body’s inside. Good for use during pregnancy.

Ultrasound scans, or sonography, are safe because, instead of radiation, they use sound waves or echos to create an image.

Ultrasound scans are used to determine fetal growth, and they can detect liver, heart, kidney or abdominal problems. Also, they can help with other forms of biopsy.

The created image is called a sonogram.

Important facts about ultrasound scans

  • Ultrasound scans are safe and widely used.
  • They are often used to check the progress of a pregnancy.
  • They are used for diagnosis or treatment.
  • No special preparation is normally necessary before an ultrasound scan.


Ultrasound scans are carried out by a sonographer.
Ultrasound scans are carried out by a sonographer.

The individual doing an ultrasound scan is called a sonograph, so radiologists, cardiologists, or other experts interpret the images.

Typically the sonographer carries a transducer, a handheld instrument, like a wand which is positioned on the skin of the patient.

Ultrasound is a sound moving through soft tissue and fluids, but it bounces backwards, or echoes, off denser surfaces. So it creates a image.

The term “ultrasound” refers to sound at a frequency which can not be heard by humans.

Typically the ultrasound for diagnostic uses varies between 2 and 18 megahertz (MHz).

Higher frequencies provide better images of quality, but are more readily absorbed by the skin and other tissues, so they can not penetrate as deeply as lower frequencies.

Higher frequencies penetrate deeper, but inferior in image quality.

How does it capture an image?

Ultrasound, for example, passes through blood in the heart cavity, but if it reaches a heart valve, it returns, or bounces back.

If there are no gallstones, it will pass straight into the gallbladder but if there are stones, it will bounce back from them.

The denser the target hits the scanner, the more it bounces back.

This bouncing back, or echo, gives its features to the ultrasonic picture. Increasing shades of grey represent increasing densities.

Ultrasound transducers

The transducer, or wand, is usually mounted on the patient’s body surface but certain kinds are mounted internally.

This will include photos which are simpler and more detailed.

Examples include:

  • an endovaginal transducer, for use in the vagina
  • an endorectal transducer, for use in the rectum
  • a transesophageal transducer, passed down the patient’s throat for use in the esophagus

Some very small transducers can be placed on a catheter’s end and inserted into the blood vessels to examine the blood vessel walls.


Ultrasound image
Ultrasound images are made from reflected sound, and a diagnosis can then be made.

Ultrasound is commonly used during procedures such as biopsies, for diagnosis, treatment and guidance.

It may be used to analyze internal organs including the liver and kidneys, the pancreas, the thyroid gland, the testes among ovaries, and others.

An ultrasonic scan will show whether a lump is a tumor. This may be cancerous, or a cyst overflowing with blood.

It can help to diagnose soft tissue disorders, muscles, blood vessels, tendons, and joints. A frozen shoulder, tennis elbow, carpal tunnel syndrome and others are examined.

Circulatory problems

Ultrasound Doppler can measure blood flow in a vessel or blood pressure. It can assess blood flow rate and any obstructions.

One example of Doppler ultrasound is an echocardiogram (ECG). It can be used to construct cardiovascular system images, and at different points to measure blood flow and cardiac tissue movement.

An ultrasound from Doppler can determine the function and condition of cardiac valve areas, any heart defects, valvular regurgitation, or blood leakage from valves, and it can demonstrate how well the heart pumps out blood.

It can also be used to:

  • examine the walls of blood vessels
  • check for DVT or an aneurysm
  • check fetal heart and heartbeat
  • evaluate for plaque buildup and clots
  • assess for blockages or narrowing of arteries

A carotid duplex is a type of carotid ultrasonography which may include an ultrasonic Doppler. This will demonstrate how blood cells pass through the arteries of the carotid.

Ultrasound in anesthesiology

Ultrasound is commonly used by anesthetists to direct a needle past nerves with anesthetic solutions.

An ultrasound can be performed in a doctor’s office, in an ambulatory clinic, or in a hospital.

Most scans take 20 to 60 minutes to complete. Usually, it’s not uncomfortable, and no noise.

No special planning is required in most cases, but patients may want to wear loose-fitting and comfortable clothing.

If the liver or gallbladder is affected, the patient can have to either run for several hours before the operation, or eat nothing.

The patient should drink plenty of water for a scan during pregnancy, and especially early pregnancy, and try to avoid urinating for some time before the test.

The scan provides a better image of the uterus when the bladder is full.

The scan normally takes place inside a hospital’s radiology department. The test is carried out by a doctor or a specially trained sonographer.

External ultrasound

The sonographer places a lubricating gel on the skin of the patient, and puts a transducer above the lubricated surface.

The transducer is placed over the body part which needs to be checked. Examples include ultrasonic tests of the heart of a patient or a fetus in the uterus.

The patient should not be feeling pain or discomfort. They are just going to feel the transducer over the skin.

The full bladder can cause slight discomfort during pregnancy.

Internal ultrasound

If it is appropriate to examine the internal reproductive organs or urinary system, the transducer can be positioned in a man’s rectum or in a woman’s vagina.

For example, an endoscope can be used to examine any portion of the digestive system, the esophagus, chest lymph nodes, or the stomach.

At the end of the endoscope, which was placed into the patient’s body, a light and an ultrasound tool was connected, normally through the mouth.

Patients are given drugs prior to the operation to reduce any discomfort.

Internal ultrasonic scans are less convenient than external ones, and the chance of internal bleeding is small.


Most types of ultrasound are noninvasive, and do not involve exposure to ionizing radiation. It’s believed the procedure is very healthy.

Nonetheless, unnecessary “keepsake” scans during pregnancy are not recommended because the long-term risks are not known. Ultrasound is recommended only when medically needed during pregnancy.

Anyone who’s allergic to latex will Inform their doctor not to use a latex-covered probe.

Blood / Hematology

Types and normal ranges of kidney function tests



Kidney function tests are basic procedures that use blood or urine to diagnose kidney abnormalities. A variety of kidney function tests are available to assess various aspects of renal health.

A kidney function test can detect sluggish waste filtering. Another test may detect protein leakage from the kidneys.

In cases where a doctor suspects a kidney disease, routine testing can help all individuals.

According to the National Kidney Foundation, 1 in 3 adults in the US is at risk for kidney disease, and many early cases show no symptoms. It’s important to detect and treat this condition early to avoid permanent damage.

In this article, you’ll learn about kidney function tests and their results.

What is it?

consulting a doctor

Kidney function tests use blood or urine to assess many elements of kidney health.

Doctors frequently request multiple tests to provide a comprehensive picture of kidney health.

The kidneys are vital to the body’s wellbeing. Their major function is to filter waste from the blood and excrete it in the urine.

Kidney disease can hinder the kidneys from filtering waste effectively, causing hazardous symptoms.

Regular testing may help detect disorders like kidney disease early on, halting its disease.

Doctors may also arrange imaging or a biopsy to learn more about the kidney.

Continue reading to learn about kidney function testing.

Urine tests

Pee tests may demand a little sample or all of a person’s urine in 24 hours.


Urinalysis helps doctors uncover underlying disorders or decide which test to employ next. Urinalysis can discover unwanted particles in urine such as:

  • sugar
  • protein
  • pus
  • blood
  • bacteria

A positive test for one or more of these particles means:

The microalbuminuria or albumin-to-creatine ratio

Both tests require a little urine sample. Both aid in detecting albumin in urine.

Albumin is an important protein in the blood. Not doing your job properly if your kidneys excrete too much albumin.

30 mg/g or less urine albumin is normal. Any higher may indicate renal disease.

As a result, microalbuminuria can detect even minute levels of protein in the urine.

Even if other urine protein tests are negative, people at increased risk of renal disease may need a microalbuminuria test.

Creatine clearance

A creatine clearance test involves both blood and urine. It entails taking a 24-hour urine sample and a blood sample.

Creatine is a naturally occurring waste product in the body from muscular use.

Doctors compare creatine levels in urine to blood levels. This chart compares the amount of waste the kidneys filter out, which may indicate their general health.

Blood tests

An arm blood test requires a doctor or nurse to extract a little amount of blood from the patient. The person may need to fast or take the test early in the morning.

Serum creatine test

Serum creatine levels that are excessively high could indicate that the kidneys aren’t doing their job properly. As part of the creatine clearance test, doctors will also prescribe a serum creatine test.

Serum creatine levels exceeding 1.2 for women and 1.4 for men, according to the National Kidney Foundation, may be an early warning that the kidneys aren’t working properly. As renal disease advances, these figures may grow even higher.

This test can also be used to calculate a person’s glomerular filtration rate (GFR) to confirm a diagnosis or to order additional tests to double-check the results.

The GFR test adjusts the findings of a serum creatine test for a variety of parameters, including age, gender, and race. A GFR of 60 or higher is considered normal. A GFR of 60 or less is indicative of renal disease.

Blood urea nitrogen test

The blood urea nitrogen (BUN) test looks for urea nitrogen and other waste products in the blood.

When proteins in food break down, urea nitrogen is produced, and high amounts may indicate that the kidneys are not filtering these waste products adequately.

BUN levels typically range from 7 to 20 milligrammes per deciliter. Higher levels could indicate a kidney-related underlying condition.

However, numerous other factors, such as drugs or antibiotics, might impact BUN levels. A diet high in protein may also have an impact on levels.

To acquire a better picture of how successfully the kidney filters this waste, doctors would often compare these results to the results of a creatine test.

Imaging tests

Imaging scans may aid in the detection of any physical abnormalities to the kidneys, such as injuries or kidney stones.


To take photos, ultrasound exams use innocuous sound waves. An ultrasound may be ordered by a doctor to check for changes in the shape or position of the kidneys. An ultrasound may also be requested to screen for tumours or obstructions, such as kidney stones.

CT scans

A CT scan is a procedure that employs a sequence of X-ray images to build a 3D image of the kidneys. It could aid in the detection of any structural alterations or deformations in the kidney.

A dye injection is sometimes required for the scan, which might be problematic for people who have kidney disease.


Doctors may recommend a kidney biopsy in some instances. This is a procedure in which a tiny needle is inserted into the kidney to remove renal tissue. The tissue will be sent to a lab for testing by the doctor.

When doctors need to diagnose a specific disease and determine how well it might react to treatment, they may perform a biopsy. A biopsy may also be used to assess the progression of renal disease.


Multiple positive test findings indicate that there is a problem with the kidneys.

Each of these tests provides doctors with a more complete view of a person’s overall kidney health. The scans can also detect renal disease signs, allowing for the ordering of additional tests.

Doctors will strive to completely identify the condition and design a treatment strategy once they have determined that there is a problem with the kidneys.

Kidney failure can be caused by a variety of underlying diseases. In order to discover the best treatment for each instance, a comprehensive diagnosis is required.


Renal function tests are an important element in diagnosing and treating kidney problems. Even if there are no symptoms, some people may need to be tested on a regular basis.

People at increased risk for kidney problems should get frequent kidney function testing, according to the National Institute of Diabetes and Digestive and Kidney DiseasesTrusted Source. Those with the following people are at a high risk:

Regular renal function testing can help detect kidney abnormalities early on, when the outlook is the best.

People can assist prevent the condition from progressing by sticking to a treatment plan. The best method to evaluate and manage any indicators of kidney damage or underlying issues is to work directly with a doctor.



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Cardiovascular / Cardiology

What is an echocardiogram?



An echocardiogram is an ultrasound image of the heart. It can help doctors diagnose a range of heart problems.

Doctors use echocardiograms to help them diagnose heart problems, such as damaged cardiac tissue, chamber enlargement, stiffening of the heart muscle, blood clots in the heart, fluid around the heart, and damaged or poorly functioning heart valves.

In this article, we explain how doctors use echocardiograms, what to expect during the test, and how to interpret the results.

What is it?


Ultrasound waves are used in echocardiography to create a picture of the heart, which is referred to as an echocardiogram (echo).

It is a minimally invasive medical technique that emits no radiation and has few negative effects.

A doctor can see the following things during an echocardiogram:

  • any blood clots in the heart
  • areas of damaged or weak cardiac muscle tissue
  • the size and thickness of the chambers
  • how the valves of the heart are functioning
  • problems affecting the pericardium, which is the fluid-filled sac around the heart
  • causes of a stroke
  • the direction of blood flow through the heart

Doctors frequently utilize echocardiography to assess a person’s overall heart health, particularly following a heart attack or stroke.

What is the procedure?

Echocardiograms are simple, noninvasive procedures that require little preparation.

We’ll go over what to expect before, during, and after an echocardiography in the sections below.


The person does not need to prepare if the echocardiogram is taken from the outside of the body by a healthcare expert.

A doctor will advise people who are getting a transesophageal echocardiography to avoid eating or drinking anything for at least 6 hours before the procedure. Following the local anesthetic wears off, people can resume eating and drinking 1–2 hours after the echocardiography.

During the test

The transthoracic (external) echocardiography will be performed by a sonographer. Sonographers are medical practitioners who specialize in producing images and movies for diagnostic purposes utilizing ultrasound instruments.

The person getting the echocardiography will take off their clothes from the waist up throughout the procedure. If they want to be covered during the exam, they can wear a hospital gown.

The sonographer will then urge the patient to lie on their back or left side on a table. They may inject a saline solution or dye into the veins of the patient to make the heart seem more distinct on an echocardiogram.

The type of echocardiography determines the procedure. Consider the following example:

Transthoracic echocardiogram

The sonographer will apply a gel to the chest if a doctor has ordered a transthoracic echocardiogram. After that, the sonographer will move the transducer across the chest to obtain various images of the heart.

The sonographer may ask someone to change positions or take or hold a deep breath throughout the examination. To gain a better view of the heart, they could press the transducer into the chest.

Transesophageal echocardiogram

If a clinician wants more detailed or sharper images of the heart than a transthoracic echocardiogram can provide, they may perform a transesophageal echocardiogram.

The person may be given a small sedative to help relax the muscles in their throat and a topical anesthetic to block the gag reflex during a transesophageal echocardiogram.

A doctor will guide a small transducer on the end of a long tube down the throat and esophagus until it reaches the back of the heart once the sedative and local anesthetic have taken effect.

As the doctor moves the transducer around the esophagus, the sonographer will record images of the heart. After swallowing the probe, the user should not feel the transducer or tube in their esophagus.

After the test

After a transthoracic echocardiography, most people can resume their normal activities.

After a transesophageal echocardiography, people may be required to stay at the hospital or healthcare center for a few hours. They may have a sore throat at first, but it should go away within a day or two.

If you were given a sedative prior to the exam, you should not drive for many hours afterward.

What does it diagnose?

Echocardiograms allow doctors to see the size, structure, and activity of different parts of the heart.

This allows them to identify heart abnormalities, assess the need for additional tests, decide their next actions, and monitor changes and improvements.

Doctors may use this approach to examine for signs or symptoms that could indicate the following:

  • Heart attack: The test can look for anomalies in the heart muscle tissue’s blood supply, as well as wall irregularities and blood flow, all of which can signal a heart attack.
  • Blood clots (thrombus) or tumors: In a study published in 2021, echo was proven to be a viable alternative to cardiac magnetic resonance in detecting thrombosis. According to a 2020 study, it is also an important noninvasive method for detecting heart masses such as malignancies.
  • Atherosclerosis and coronary artery disease (CAD): While an echo cannot detect artery blockages, narrowing and obstructed arteries can impair the heart’s ability to pump blood and disrupt the heart’s wall motion. This is more noticeable during times of stress, making a stress echo a useful diagnostic tool.
  • Aortic aneurysm and aortic dissection: An echo can detect a wide, weaker aorta, as well as unruptured aneurysms and their size, as well as fibrosis and thrombus formation in the vessel.
  • Cardiomyopathy: The test can determine the size and function of the heart and link it to factors such as wall thickness, weak heart muscle, leaky heart valves, heart failure, and high blood pressure.
  • Pulmonary hypertension: The test can measure heart pressure, which can indicate the presence of pulmonary hypertension and aid doctors in determining the following steps in the diagnosis.
  • Congenital heart disease: In newborns and early children, the test can detect congenital cardiac problems such as septal defects and holes.
  • Heart valve disease: The test checks for leakage, constriction, infection, and blockage in heart valves, as well as irregular cardiac blood flow.
  • Problems with the pericardium: The test can determine whether the pericardium (the sac that surrounds the heart) is inflamed (pericarditis) or has become filled with fluid or blood (pericardial effusion).
  • Heart failure: It can detect cardiac muscle that is weak, stiff, or thickened, which can be a symptom of heart failure.

Doctors frequently utilize the test to determine the cause of an abnormal electrical heart test, known as an electrocardiogram (EKG).

The method is also used to track how effectively the heart responds to various heart treatments, such as heart failure, drugs, prosthetic valves, and pacemakers.

If a doctor suspects a patient has cardiac abnormalities, an echocardiography will be ordered. The following are signs and symptoms that could suggest a cardiac condition:

Types of echocardiogram

Different types of echocardiograms are available, all of which use high-frequency sound waves. The following are some of the most frequent types.

The most common form of echocardiography is the transthoracic echocardiogram.

An ultrasound wand called a transducer is placed on the outside of the chest, near the heart, for this test. Sound waves are sent through the chest and into the heart via the device.

Sound waves move more easily when a gel is applied to the chest. These waves bounce off the heart and appear on a screen as images of the heart’s architecture.

Transesophageal echocardiogram

A thinner transducer attached to the end of a lengthy tube is used in a transesophageal echocardiogram. The tube will be swallowed and inserted into the esophagus, which connects the mouth to the stomach and runs behind the heart.

Because it gives a “close up” view of the heart, this type of echocardiography produces more detailed images of the heart than the typical transthoracic echocardiogram.

Doppler ultrasound

Doppler ultrasounds are used by doctors to check blood flow. They accomplish this by producing sound waves at specified frequencies and observing how the waves bounce off and return to the transducer.

Color doppler ultrasounds can be used by doctors to map the direction and velocity of blood flow in the heart. The blood flowing toward the transducer shows red, while the blood flowing away appears blue. It can also tell you how bad the blockages are.

A doppler ultrasound can detect issues with valves or holes in the heart’s walls, as well as let doctors examine how blood flows through it.

3D echocardiogram

A detailed 3D image of the heart is created through a 3D echocardiography. 3D echocardiograms can be used by doctors to:

  • plan heart valve or structural interventional surgery
  • image complex structures within the heart
  • assess valve functionality in people who have heart failure
  • assess the function of the heart in 3D
  • diagnose heart problems in infants and children

Stress echocardiogram

A doctor can order an echocardiogram as part of a stress test. A stress test involves physical exercise, such as walking, jogging on a treadmill, or riding a bike.

During the test, the doctor will keep track of your heart rate, blood pressure, and electrical activity in your heart.

Before and after the activity, a sonographer will do a transthoracic echocardiogram.

Stress tests are used by doctors to diagnose:

Point-of-care (POC) echocardiogram

A POC echocardiogram is a type of echocardiogram that can be performed at a patient’s bedside by a clinician. These can assist a doctor in answering specific inquiries about possible differential diagnoses.

Limited and focused POC echo are the two types of POC echo.

A limited echocardiogram aids a clinician in determining the cause and repercussions of a heart injury. A focused echo is used by a doctor to assist narrow down the list of other possible diagnoses or to answer a specific query.

With each heartbeat, a POC echocardiogram can determine how well the left or right ventricles pump blood.

Fetal echocardiogram

A fetal echocardiogram allows doctors to see the heart of an unborn baby. This check is normally done between 18 and 22 weeks of pregnancy. Because echocardiograms do not involve radiation, they are safe for both the mother and the infant.

Interpreting the results

The echocardiographic images will be sent to the doctor who requested the test by the sonographer after the exam. The doctor will examine the photos for indicators of cardiac disease, such as:

  • abnormal chamber size
  • poorly functioning valves
  • chamber size
  • masses in the heart, such as blood clots or tumors
  • damaged heart muscle tissue
  • pumping function of the heart
  • thick or thin ventricle walls

What can it miss?

Echocardiograms are very useful in detecting structural heart abnormalities. They may, however, not be the ideal way to check the coronary arteries.

Blockages can cause the structure of the heart. Changes in cardiac function, weak muscles, or thinner heart walls are frequently detected by doctors, prompting them to order additional tests such as a coronary angiogram.

Echocardiograms cannot detect conduction disorders or electrical difficulties that impact the heart’s rhythm, but they can measure the effects of these abnormalities on the heart.

Echocardiogram vs. electrocardiogram

An echocardiogram should not be confused with an electrocardiogram, or EKG, which is another diagnostic procedure. The electrical impulses or waves that flow through cardiac muscle tissue are measured by an EKG.

The electrical activity in the heart causes the heart muscle tissues to contract and relax, resulting in the rhythmic heartbeat that a stethoscope can detect.

Electrodes are placed on the skin of the chest, arms, or legs by a qualified technician, nurse, or doctor. These electrodes capture electrical activity and transfer it to a computer, which translates it into a graph that a doctor may see.

Are there any side effects?

An echocardiogram has a very minimal risk of problems or side effects. When the sonographer guides the tube down the throat during a transesophageal electrocardiogram, the person’s gag reflex may be triggered. After the exam, some people may experience a sore throat.

A significant consequence, such as injury to the throat, vocal cords, or esophagus, can occur very rarely as a result of the transesophageal echocardiogram.

Some people may have an adverse reaction to local anesthetics, sedatives, contrast dyes, or saline used during the exam. Only use contrast dyes if absolutely essential when pregnant.

The following are some of the potential negative effects of contrast dyes:

During a stress test, some people may experience changes in blood pressure or a reduction in oxygen delivery to the heart. In the event that a person has any issues during the assessment, a stress test will be performed in a fully equipped medical facility.

When a person is given sedatives, the stomach contents have a risk of entering the lungs. To avoid this, the patient will be asked to come to the surgery on an empty stomach.


Doctors utilize echocardiography to diagnose heart-related issues. A doctor will assess how well a person’s heart pumps blood during the test.

Doctors can also use echocardiography to check for indicators of cardiac disease such weak heart muscle, blood clots inside the heart, or malfunctioning heart valves.

An echocardiogram may be ordered by a clinician if a patient exhibits symptoms of heart disease, such as:

  • heart murmurs
  • irregular heartbeat
  • shortness of breath
  • abnormal blood pressure
  • leg swelling

The test has a low risk of serious problems or side effects in general. However, some people may have discomfort, and other people may be allergic to the contrast material or anesthesia.



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Blood / Hematology

TSH levels: All you need to know



Thyroid-stimulating hormone (TSH) testing determines the level of TSH in the blood. The results show how well a person’s thyroid is working.

TSH test results can be used by doctors to diagnose thyroid problems such as hypothyroidism and hyperthyroidism.

TSH, a hormone that stimulates the thyroid gland, is produced by the pituitary gland.

The thyroid gland is a butterfly-shaped gland located in the throat. It secretes hormones that aid in the regulation of various biological systems, including metabolism, heart rate, and body temperature.

The TSH test and its findings are described in this article. We also go over what high and low TSH values mean and what therapies are available.

Typical TSH range

MNT-infographic_guide infographic by Diego Sabogal 1401179-TSH-levels-original
MNT-infographic_guide infographic by Diego Sabogal 1401179-TSH-levels-original

The typical range is determined by a person’s age and whether or not she is pregnant.

As a person gets older, the ranges tend to widen. TSH levels in males and females have not been found to differ consistently in studies.

However, doctors generally consider levels to be within a normal range of 0.4–4.0 milliunits per liter (mU/l), according to the American Thyroid Association.

TSH levels that are normal, low (showing hyperthyroidism), and high (indicating hypothyroidism) are estimated in the table below:

HyperthyroidismNormalMild hypothyroidismHypothyroidism

These reference values are often used in laboratories.

These ranges, however, are subject to some disagreement. According to the author of a 2016 review, normal levels are more likely to be in the range of 0.5–2.5 milli-international units (mIU) per milliliter.

TSH levels by sex

Females are more likely than guys to suffer from thyroid problems. According to the Office of Women’s Health, one out of every eight females will encounter thyroid difficulties at some point in their lives. Hyperthyroidism and hypothyroidism are examples of this. Thyroid disorders are more common during pregnancy and around menopause.

TSH levels in males and females do not differ consistently, according to research. TSH levels are usually greater in females, according to some data. TSH levels are greater in females, according to 2020 studies of Chinese and French populations, although other factors, including as age, are more likely to alter TSH levels.

Thyroid problems have been connected to sexual dysfunction in certain people. Males may be affected more than females. According to a 2019 study, 59–63 percent of male hypothyroidism patients also suffer sexual dysfunction, compared to 22–46 percent of female hypothyroid patients.

TSH levels by age

Blood TSH levels tend to rise as people age, with research indicating that hypothyroidism is the most frequent thyroid condition in people over 60, and that it rises steadily with age.

According to research involving older persons, between 7–14 percent of people may have TSH levels over the upper limit of reference ranges.

Normal TSH levels in pregnancy

Pregnancy hormones naturally raise blood levels of some thyroid hormones. This is necessary for the unborn brain and nervous system to grow.

TSH levels in the blood decrease at the same time. As a result, during pregnancy, doctors adopt lower reference ranges. The lower TSH range is reduced by about 0.4 mU/l, while the higher limit is reduced by around 0.5 mU/l.

TSH levels in the blood steadily rise during the second and third trimesters, but they remain lower than in non-pregnant women.

TSH levels are carefully monitored by doctors throughout pregnancy. Having abnormally high or low levels might cause the risk of miscarriage and lead to pregnancy-related problems such as:

Normal TSH levels in children

TSH levels peak at birth and progressively decline as a child grows older. As a result, TSH levels can differ amongst children. After the newborn period, health professionals may describe moderate hypothyroidism in children as TSH levels ranging from 4.5 to 10 mU/l.

According to an older study that included data from 512 healthy children, the following table depicts TSH levels for children by age:

AgeReference ranges (mU/l)
Day of birth3.84–11.75
1 month1.18–3.57
1 year1.17–3.55
5 years1.15–3.47
12 years1.09–3.31
18 years1.05–3.16

What exactly do high levels imply?

TSH levels that are too high indicate hypothyroidism. When the thyroid produces insufficient hormones, people suffer hypothyroidism.

When a person’s thyroid gland does not generate enough hormones, the pituitary gland increases TSH production to compensate.

Hypothyroidism symptoms may include:

  • irregular or heavy menstrual periods
  • fertility problems
  • depression
  • constipation
  • fatigue
  • increased sensitivity to cold temperatures
  • dry skin
  • weight gain
  • swelling of the face and neck
  • thinning hair
  • a slow heart rate

What exactly do low levels imply?

TSH levels that are too low indicate hyperthyroidism. This is also referred to as an overactive thyroid.

When a person’s thyroid gland secretes high amounts of hormones, the pituitary gland generates less TSH.

Hyperthyroidism can cause the following symptoms:

  • difficulty sleeping
  • frequent bowel movements or diarrhea
  • weight loss
  • mood changes
  • irregular or rapid heartbeat
  • muscle weakness
  • nervousness or irritability

How to measure TSH levels

A healthcare practitioner will draw blood from a vein in the inner arm for the TSH test. They then submit the blood sample to a laboratory for analysis.

Typically, people do not need to prepare for a TSH test. If the doctor is screening the blood for more than one problem, the patient may need to fast or prepare in another way. This information will be provided by the doctor ahead of time.

A TSH test is frequently the most accurate approach to assess thyroid function. If a person’s TSH levels are excessively high or low, the doctor may need to run at least one further diagnostic test to determine the underlying cause. Specific thyroid hormones and antibodies are measured in these assays.

Factors influencing levels

TSH levels can be affected by a variety of circumstances, including age, sex, and pregnancy. TSH levels may be affected by genetic, environmental, or intrinsic causes, according to evidence. Some of these elements could be:

  • time of day and time of year
  • autoantibodies and heterophilic antibodies
  • smoking
  • pollutants
  • other conditions occurring at the same time
  • medications
  • supplements
  • ethnicity
  • diet and iodine status

Hypothyroidism treatment (high TSH levels)

Doctors can treat hypothyroidism with drugs that restore the missing thyroid hormones, such as levothyroxine.

This drug should be taken once a day or as directed. Every few months, the doctor will do further blood tests to see how well the medicine is working.

People should take levothyroxine once a day, on an empty stomach, at least half an hour before eating, according to the Food and Drug Administration (FDA).

The FDA also advises people to notify their doctor if they consume soybean flour, walnuts, dietary fiber, or cottonseed meal, as these foods can alter how the body uses levothyroxine. Drinking grapefruit juice may also delay levothyroxine absorption.

Treatment of hyperthyroidism (low TSH levels)

Treatment for hyperthyroidism focuses on lowering thyroid hormone levels in order to avoid long-term health consequences.

Beta-blockers and antithyroid medicines may be required.

Radioiodine therapy is another successful treatment. This entails ingesting a capsule or liquid containing radioactive iodine-131, which destroys thyroid hormone-producing cells. People who receive radioiodine therapy, on the other hand, may develop hypothyroidism in the future.

Severe hyperthyroidism can be treated surgically by removing the thyroid gland. Doctors frequently reserve this for patients who are unable to take first-line drugs or who have severe hyperthyroidism.


A TSH test determines the level of the hormone in the blood. The results can be used by doctors to diagnose thyroid problems such as hypothyroidism and hyperthyroidism.

Normal TSH readings can vary greatly based on age, sex, and weight. TSH reference ranges are still debatable, however for most people, the typical range is between 0.4 to 4.0 mU/l.

A thyroid that is overactive or underactive might cause health problems that interfere with a person’s daily life. TSH levels that are extremely high or low during pregnancy can cause difficulties.

More information about the TSH test and interpreting the findings can be obtained from a doctor.



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