Thyroid-Stimulating Hormone
Other names: TSH; Thyrotropin
Thyroid stimulating hormone (TSH) is a hormone, which is formed by the pituitary gland. TSH is part of the feedback loop, which helps to control thyroid hormones, including thyroxine (T4) and triiodothyronine (T3). Thyroid hormones play an important role in regulating the amount of energy used by the body; when levels decrease in the blood, the hypothalamus stimulates the production of TRH (thyrotropin releasing hormone), which in turn stimulates the production of TSH. TSH provokes the release of T3 and T4 by the thyroid gland.
When is the test used?
The TSH test is used to evaluate the function of the thyroid gland; it may be ordered along with tests to measure T3 and T4 levels. The test may be used to monitor patients who are receiving treatment for a thyroid disorder and to screen newborn babies.
The test is usually ordered when a patient has symptoms of either hyperthyroidism (overactive thyroid gland) or hypothyroidism (underactive thyroid gland). Signs of hyperthyroidism include rapid heart rate, nervousness and anxiety, weight loss, insomnia and intolerance to hot temperatures, while symptoms of hypothyroidism include weakness, weight gain, fatigue, intolerance to cold temperatures and slow heart rate.
The test may also be ordered as a routine screening test for newborn babies.
How is the test done?
The test is done by collecting and analysing a sample of blood from the patient’s arm; a needle is inserted into a vein in the arm (usually on the inside of the elbow) and the blood is drawn out using a syringe. When the doctor has a sufficient sample, the blood is bottled, labelled with the patient’s name and sent to the laboratory for analysis.
What do the test results mean?
If the results of the TSH test are high, this usually indicates that the patient has hypothyroidism (underactive thyroid gland); in rare cases, when levels are very high, this may indicate that the patient has a problem with their pituitary gland.
If the results are low, this usually indicates that the patient has hyperthyroidism (overactive thyroid gland); it may also mean that there is damage to the pituitary gland, which is preventing the production of TSH.
The test results show whether there is a problem with thyroid function; however, it cannot determine the cause of the problem and further tests will be required.
If levels are abnormal once the patient has started treatment, this may indicate that the patient is being given a dose which is either too high or too low.
Specific Blood Tests
- Specific Blood Tests
- Factor V Leiden Mutation and PT 20210 Mutation
- Ferritin Test
- Fibrinogen
- Fructosamine
- FSH Test
- G6PD
- Gastrin
- GGT
- Glucose test
- Growth hormone
- Haemoglobin
- Haptoglobin
- HbA1c test
- HDL Cholesterol Test
- Helicobacter Pylori test
- Heparin Anti-Xa
- Hepatitis A Virus
- Hepatitis B Virus
- Hepatitis C Virus
- Her-2/neu Testing
- Heterophil Antibody Titre
- High-Sensitivity C-Reactive Protein
- HIV Antibody Test
- HIV Resistance Testing
- HIV Viral Load
- IGF-1
- Immunoreactive Trypsin
- Insulin
- Iron test
- LDH
- LDL Cholesterol Test
- Lead Test
- LH Test
- Lipase Test
- Lipoprotein (a)
- Lithium
- Lupus Anticoagulant
- Lyme disease test
- Maternal screening
- Mercury, Urine and Blood
- Mycophenolic Acid
- Myoglobin Test
- Oestrogen
- Osmolality
- Overdose Drug Test
- Paracetamol
- Parathyroid Hormone
- Parvovirus B19
- PCV
- Pertussis
- Phenobarbital
- Phenytoin
- Phospate
- Platelet Count
- Porphyrins
- Potassium Test
- Prealbumin Test
- Procalcitonin
- Progesterone Test
- Prolactin
- Prostate-Specific Antigen
- Protein 24 Capsid Antigen
- Protein C and Protein S
- Protein Electrophoresis Immunofixation Electrophoresis
- Prothrombin Time
- PSEN1 Test
- PTH
- Reticulocyte count
- Rheumatoid factor
- Rubella test
- Salicylic Acid
- Serotonin
- Sex Hormone Binding Globulin
- Sickle Cell Test
- Sirolimus
- Smooth Muscle Antibody
- Sodium Test
- Soluble Mesothelin-Related Peptides
- Synacthen Test
- Syphilis Test
- Tacrolimus
- Tau protein
- Testosterone Test
- Theophylline & Caffeine
- Thiopurine s-methyltransferase
- Thyroglobulin (Tg)
- Thyroid peroxidase antibody (TPOAb)
- Thyroid-Stimulating Hormone
- Thyroxine
- TIBC, UIBC & Transferring
- TORCH Test
- Total Protein test
- Triiodothyronine
- Triglycerides Test
- Troponin test
- Urea test
- Uric Acid
- Valproic Acid
- Vancomycin
- Very Low Density Lipoprotein
- Vitamin B12 and Folate
- Vitamin D
- West Nile Virus
- White blood cell differential count
- Zinc Protoporphyrin
- Activated Clotting Time
- ACTH
- Albumin
- Aldosterone and Renin
- Alkaline Phosphatase Test
- Allergen-Specific IgE Antibody Test
- Alpha-1 Antitrypsin
- Alpha-Fetoprotein
- ALT
- AMA
- Ammonia
- Amylase Test
- Angiotensin Converting Enzyme
- Antinuclear Antibody
- Antithrombin
- Apolipoprotein A-I
- Apolipoprotein E Genotyping
- aPTT
- AST
- Bicarbonate
- Bilirubin
- Blood cultures
- Blood film
- Blood Gas Tests
- Blood Ketones
- Brain Natriuretic Peptide
- BRCA-1 & BRCA-2
- CA 125
- Cancer Antigen 15-3
- Cancer Antigen 19-9
- C-peptide
- Caeruloplasmin
- Calcitonin
- Calcium Test
- Carbamazepine
- Cardiac Risk Assessment
- Cardiolipin Antobodies
- Catecholamines, Plasma and Urine
- CCP
- CD4 and CD8
- CEA Test
- CF Gene Mutation Testing
- Chickenpox and Shingles Tests
- Chloride Test
- Cholesterol Test
- Chlorinesterase Test
- Chromogranin A
- Ciclosporin
- CMV
- Coagulation Factors
- Coeliac Disease Tests
- Copper
- Cortisol Test
- Creatine Kinase CK-MB Test
- Creatine Kinase Test
- Creatinine
- Creatinine Clearance
- C-Reactive Protein
- Cystatin C
- D-Dimer
- DHEAS
- Digoxin
- Direct LDL cholesterol
- eGFR - Calc. Creatinine Clearance
- Electrolytes
- Epstein-Barr Virus Antibodies
- Erythrocyte Sedimentation Rate
- Erythropoietin
- Ethanol
Blood Test Guide
- Blood Tests
- Types of blood tests
- what to expect
- What are the risks of blood tests?
- What do blood tests show?
- Specific Blood Tests