Select a condition Absence seizures Acne ADHD Age-related macular degeneration AIDS Alzheimer's disease AMD Amebic dysentery Anal tears Angina, stable Angina, unstable Ankle sprain Anorexia Anxiety Appendicitis Arthritis Asthma in adults Asthma in children Athlete's foot Atrial fibrillation Attention deficit hyperactivity disorder (ADHD) Autism Back pain Bacterial vaginosis Bad breath Bedsores Bedwetting Bell's palsy Benign prostatic hyperplasia Bipolar disorder Bladder infection in women Blood pressure Breast cancer Breast pain Bronchiectasis Bronchiolitis Bronchitis Bulimia Bunions Burning mouth syndrome Burns and scalds Canker sores Cardiac arrest Carpal tunnel syndrome Cataracts Cellulitis and erysipelas Chickenpox Childbirth, heavy bleeding Childbirth, tear or cut Chlamydia Chronic bronchitis Chronic fatigue syndrome Chronic obstructive pulmonary disease Chronic prostatitis Chronic tension type headache Cold sores Colic in babies Colon and rectal cancer Colon and rectal cancer screening Colonic diverticular disease Common cold Conjunctivitis Constipation in adults Constipation in children COPD Crib death Deep vein thrombosis Dementia Depression in adults Depression in children Diabetes, type 1 Diabetes, type 2 Diarrhea in adults Diarrhea in children Diverticular disease Ear infection, middle ear Ear infection, outer ear Ear infection with discharge Ear infection with fluid Ear pain during air travel Ear wax Eczema Emphysema Endometriosis Enlarged prostate Epilepsy Episiotomy Erection problems Essential tremor Febrile seizures Fertility problems Fibroids Flu Gallstones Genital herpes Genital warts GERD GERD in children Glaucoma Gonorrhea Gout Group B streptococcus H. pylori infection Halitosis Hay fever Headache, chronic tension type Head lice Heart and circulation problems in diabetes Heart attack Heartburn Heart failure Heavy periods Heel pain Hemorrhoids Hepatitis B Hepatitis C Hernia Herpes, genital Herpes simplex eye infection High blood pressure High blood pressure in pregnancy High cholesterol HIV infection Hyperactivity IBS Incontinence in women Infection in newborn babies Infertility Influenza Insomnia in adults Irritable bowel syndrome Jaundice in newborn babies Jet lag Kidney infection Kidney stones Leg cramps Leg ulcers Lewy body dementia Lung cancer Lyme disease Macular degeneration Malaria prevention Manic depression Mastalgia Measles, mumps and rubella: prevention Melanoma Meniere's disease Meningococcal disease Menopause Migraine in adults Migraine in children MMR prevention Morning sickness Multiple sclerosis Nail infection, fungal Neck pain Nicotine addiction Non-Hodgkin's lymphoma Nosebleeds in children Obesity Obsessive-compulsive disorder OCD Oral thrush Osteoarthritis Osteoporosis Ovarian cancer Painful periods Pancreas cancer Panic attacks Parkinson's disease PCOS Pelvic inflammatory disease Perineal care Peripheral arterial disease Peripheral vascular disease Pneumonia Polycystic ovary syndrome Postpartum depression Postpartum hemorrhage Post-traumatic stress disorder Preeclampsia Pregnancy, nausea Premature birth Pressure sores Prostate cancer Prostatitis, chronic Psoriasis PTSD Raynaud's disease Rectal cancer screening Recurrent cystitis Reflux in children Rheumatoid arthritis Scabies Schizophrenia Seasonal allergy Shoulder pain Sickle cell anemia Sickle cell disease SIDS Sinusitis Skin cancer (melanoma) Skin cancer (squamous cell) Sleep apnea Sleep problems in children Slipped disk Smoking Sore throat Stomach ulcers Stress headache Stress incontinence Stroke, emergency care Stroke prevention Sudden infant death syndrome Swimmer's ear Tennis elbow Tension headache Testicular cancer Thrush (oral) Tic douloureux Tinnitus Tonsillitis Toxoplasmosis in pregnancy Trigeminal neuralgia Underactive thyroid Urinary tract infections in children Varicocele Varicose veins Vascular dementia Warts Whiplash Wisdom teeth, impacted Wrinkles Yeast infection, vagina

Select treatment area Bladder & Kidneys Blood Brain & nervous system Cancer Children's health Diabetes Digestive system Ear, nose & throat Eating & weight Eyes Fertility Heart and circulation Hormones Infections Lungs & breathing Men's health Mental health Mouth Muscles & bones Pregnancy & childbirth Sexual health Skin Sleep Staying healthy Travel health Women's health

To check whether you have an underactive thyroid gland, your doctor will ask you some questions, examine your neck and do some blood tests.

Your doctor might ask you some of these questions.^{1 2}

• Do you feel very tired?
• Have you gained weight?
• Do you have constipation?
• Do you feel the cold?
• If you are a woman, are your periods heavier than usual?
• Have you noticed a swelling in your neck?

Your doctor might ask you when your symptoms started, and if they all started at the same time. He or she might also ask you about changes to your hair, skin and voice.

Your doctor will probably ask whether any members of your family have thyroid problems. He or she will also want to know about any operations or X-rays you've had, any illnesses you've had and any medicines you're taking.

Your doctor will examine your neck to see if your thyroid gland is bigger than usual. Your doctor may also:

• Measure your weight
• Examine your skin and hair
• Test the strength of your muscles
• Check your blood pressure and pulse. This is because an underactive thyroid gland can affect your heart.

Your doctor will order blood tests to check the levels of hormones in your blood. These hormones are thyroid-stimulating hormone (TSH) and thyroxine (T4). If you have more TSH than normal, or less T4, you may have an underactive thyroid gland.

If your TSH level is only slightly raised and your T4 level is normal, you may have mild hypothyroidism.

Your doctor will also check for thyroid antibodies in your blood. Your immune system makes antibodies to fight infections. If you have thyroid antibodies in your blood, you may have autoimmune thyroid disease. To read more about things that can cause the condition, see What is an underactive thyroid?

Your might also have blood tests to look for conditions that you can get alongside an underactive thyroid gland, such as raised cholesterol.

Your doctor may refer you to a doctor who specializes in hormones (an endocrinologist) if you have any of the following.^{1 3}

• Any other endocrine disease, such as Addison's disease (a disease of the adrenal gland) or vitiligo (where you get white patches on your skin).
• If you are pregnant. To read more, see Pregnancy and an underactive thyroid gland.
• A heart condition.
• An enlarged thyroid gland.
• You are taking medicine that might be causing your thyroid problem.

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.