Tests for HbA1c, Thyroid Profile, and Lipids

What are HbA1c, Thyroid, and Lipids?

HbA1c is the term used for glycosylated haemoglobin. HbA1c is found in the blood and is formed of haemoglobin (the oxygen-carrier within red blood cells) and sugar (glucose) molecules (from digested food). The more blood glucose there is in the blood, the more haemoglobin is glycosylated. Blood glucose level is controlled by insulin produced in the pancreas.

The thyroid is a gland in the neck that regulates the body's metabolism using two hormones, thyroxine (known as T4, and produced by the thyroid) and tri-iodothyronine (T3, produced from T4, mostly by non-thyroid tissues). T4 and T3 are found in the blood, where their levels are controlled by the action of thyroid-stimulating hormone (TSH, produced in the pituitary gland) on the thyroid.

Fats in the blood are called lipids. Cholesterol and triglycerides are lipids that are made in the liver or from food. They are transported in the blood as lipoproteins, formed of fats and proteins. Lipoproteins that transport cholesterol include low-density lipoproteins (LDL-cholesterol or "bad" cholesterol) and high-density lipoprotein (HDL-cholesterol or "good" cholesterol); those that carry triglycerides include very low-density lipoproteins (VLDL) and chylomicrons. There is little change in levels of cholesterol, LDL, HDL, and VLDL after a meal; their levels indicate your general diet and lifestyle. However, chylomicron levels in the blood increase after a meal. The liver produces about 80% of the cholesterol in the body, and also removes it; the remainder is from the diet.

What are Tests for HbA1c, Thyroid, and Lipids?

A test for your:

• HbA1c measures the glucose level in the blood, either after fasting (when you do not eat or drink, except for water) usually for 8-12 hours or eating your meals as usual.
• Thyroid profile measures the levels of thyroid hormones T4 and T3, the pituitary hormone TSH, the enzyme thyroid peroxidase, the protein thyroglobulin, and the antibodies thyroglobulin antibodies and thyroid peroxidase antibodies, involved with thyroid function in the blood. Typically, T4 and TSH are checked and, if these are abnormal, then the other factors may be ordered.
• Lipids measures the levels of total cholesterol LDL-cholesterol, HDL-cholesterol, total cholesterol to HDL-cholesterol ratio, non-HDL-cholesterol, and triglycerides in the blood.

Why are HbA1c, Thyroid Profile, and Lipids important?

The HbA1C, thyroid-associated components, and lipids are all used to monitor the health of a person. Routine checks can help maintain good health and prevent serious complications.

Over time, high blood glucose (HbA1C) levels (called hyperglycaemia) can lead to prediabetes, when your blood sugar level is higher than normal but not so high as to be considered diabetes, and then to diabetes. The blood vessels are damaged, which hinders blood circulation, leading to high blood pressure, heart disease, stroke, kidney disease, eye complications, and nerve damage. Type 2 diabetes is preventable, most common, and results from the body not producing enough or responding to the hormone insulin that regulates blood glucose levels. Type 1 diabetes, caused by a malfunctioning immune system or certain genes (inherited), occurs when cells in the pancreas cannot produce insulin.

Thyroid hormones help regulate the metabolism of the cells in your body (the speed of cell processes). If the thyroid gland secretes too much thyroid hormone (hyperthyroidism), the cells increase their activity, which can lead to weight loss, frequent bowel movements, increased heart rate and heart irregularities, anxiety, osteoporosis, and eye problems. With too little thyroid hormone secretion (hypothyroidism), the rate of cell activity slows, which can result in weight gain, constipation, slow heart rate, depression, high cholesterol levels, cardiovascular disease (CVD), and hearing loss.

Cholesterol and triglycerides are essential to health. Cholesterol is used to make cell walls, hormones and vitamin D, while triglycerides provide energy for muscles and organs, and body heat. In excess, "bad" LDL-cholesterol and triglycerides increase the risk of CVD, leading to heart attacks and strokes.

Who should monitor their HbA1c, Thyroid Profile, and Lipids?

Regular health checks of HbA1c, thyroid function, and lipids help to maintain good health as they look for both risk factors and signs of disease. If you are healthy, monitoring for blood levels of glucose levels, thyroid hormones and associated factors, and lipids may be made every 1 to 5 years, depending on your age. However, the frequency of these checks may vary if you have related or certain other health conditions or take medicines.

Blood sugar levels should be monitored if you have diabetes, uncontrolled diabetes, or prediabetes. You should get checked if you get symptoms of diabetes (particularly an increase in thirst or need to pass water, tiredness, and weight loss). Getting tested means that you may be able to prevent either diabetes or the serious complications of diabetes. Testing is usually done every 3-6 months, but will depend on your treatment regimen and individual circumstances.

Checking thyroid function is important if you have unexplained changes in health, such as body weight, bowel habits, mood, or heart rate, or have an autoimmune disease. Testing thyroid function is also required for people with hypothyroidism to monitor thyroid hormone replacement therapy, and people who are on or have had treatment for hyperthyroidism or irradiation therapy for head and neck cancer. How often you are tested will depend on your treatment.

You may not have any symptoms if you have a high cholesterol level. On the other hand, as fatty deposits (plaques) build up in your arteries, you could get breathless, light-headedness and chest pain or even have a heart attack or stroke. You should be checked if you have never been tested and are over 40 years, or are overweight, male, have diabetes, or your relatives have high cholesterol or heart disease. Cholesterol checks in healthy adults should be every 5 years, but will be more frequent if you have CVD or risk factors for CVD.

How to test for HbA1c, Thyroid Profile, and Lipids?

Two small blood samples are needed to carry out these tests. The blood samples are collected by you using a simple test kit, provided by The Online Clinic. There are full instructions provided on what to do, so read these before starting. We will also let you know if you should avoid eating and drinking for 8-12 hours before taking your blood samples.

Briefly, after cleaning an area of skin on your little finger, place the lancet on this area and press to activate it. The skin has been pricked and a blood drop collects. Wipe this drop with a clean tissue and collect the following blood drops into the collection tube up to the line. If the blood drops stop forming, prick the skin again using a new lancet on the other little finger and collect the rest of the blood sample. Seal the blood collection tube and gently invert the tube 5-10 times. Remember you need two to provide two blood samples. Fill in the tube labels and stick them to the tubes, before putting in the packing wallet for sending. The Online Clinic doctor will receive your test results and explain to you what they mean.

What do HbA1c, Thyroid Profile, and Lipid Test results indicate?

The HbA1C test will show the level of glucose in your blood. Prediabetes may be indicated if your blood glucose levels are slightly above normal, and diabetes is diagnosed if your blood glucose levels are much higher than normal (called hyperglycaemia). Abnormal levels may mean that your pancreas is not producing enough insulin.

The thyroid hormones T4 and TSH indicate if your thyroid and pituitary glands are working properly. Too much T4 in the blood indicates hyperthyroidism, too little indicates hypothyroidism.

A high cholesterol level could mean that you have a problem with your liver function, but usually indicates that you need to make changes to your diet and lifestyle. Hyperlipidaemia is the term used when you have too much lipid (cholesterol and triglycerides) in your blood; hypercholesterolemia indicates that there is too much "bad" LDL-cholesterol and non-HDL cholesterol in your blood.

How to maintain or achieve good HbA1c, Thyroid Profile, and Lipid levels

Generally, the key to maintaining good health lies in your lifestyle. There are five major components for a healthy lifestyle: a healthy diet, not smoking, physical exercise, moderate alcohol consumption and a normal body mass index (linked to body weight). Additionally, you should have regular check-ups about every three years if you are younger, and every year if you are older.

Click on the links to read more on HbA1C, Diabetes Testing, Thyroid Function, and the Blood Lipids Profile.

Reviewed by: Dr Loraine Haslam MBBS, DRCOG, DFSRH, LoC SDI, LoC IUT, MRCGP
GMC registration number: 4524038
Date: 27 March 2023
Next review: 26 March 2025
All UK registered doctors can have their registration checked on
The Medical Register at the GMC website.