Hypothyroidism

Question 1

Definition?

Answer 1

Clinical state resulting from underproduction of T3 and T4 due to an underactive thyroid gland or in secondary, underactive pituitary gland.

Question 2

RF?

Answer 2

• Iodine deficiency
• Female
• Middle age
• FH of AI thyroiditis
• AI-GD, PP, Turners/Down’s
• Pulmonary HT
• MS
• Radiotherapy, amiodarone, lithium

Question 3

Ddx?

Answer 3

• Central of secondary hypothyroidism-free T4 is low and TSH may be low, normal, or slightly elevated. MRI may reveal sellar or parasellar pathology.
• Depression-elevated TSH
• Alzheimer’s-normal TSH, cerebral atrophy
• Anaemia- FBC

Question 4

Epidemiology?

Answer 4

Age: 30-50
Sex: Women
Ethnicity: White
Prevalence:

Question 5

Aetiology?

Answer 5

Hashimotos
postpartum
DQ
congenital
riedel

Question 6

CP?

Answer 6

• Fatigue
• Cold intolerance
• Less sweating
• Hair loss, brittle nails and cold dry skin
• Weight gain
• Constipation
• Bradycardia
• Myopathy
• Woltman’s sign-delayed relaxation
• Entrapment symptoms
• Hoarse voice
• Pretibial and periorbital oedema
• Hyperprolactinoma-menorrhagia, galactorrhoea, low libido, ED
• Depression
• HT
• Goitre

Question 7

Pathophysiology?

Answer 7

• Inadequate production of thyroid hormone
• Hashimoto’s thyroiditis-autoimmune inflammation-anti-thyroid peroxidase antibodies, and anti-thyroglobulin antibody formation
• Destruction of follicular cells and thyroglobulin.
• Iodine deficiency-needed for hormone production
• Treatment for hyperthyroidism-carbimazole, PTU, propylthiouracil, radioactive iodine and surgery
• Medications-lithium inhibits production, amiodarone interferes with production and metabolism
• Secondary-
Hypopituitarism-tumours, infections , vascular (Sheehan syndrome after post-partum haemorrhage) or radiotherapy to pituitary gland

Question 8

Investigations-first line?

Answer 8

TFT's, thyroid status exam
p-high TSH, low T4 and T4
S/T-low TSH, low T3/T4
S-high TSH,normal T3/T4
E-normal TSH, low T3/T4

Question 9

I-second line?

Answer 9

• FBC-anaemia
• Cholesterol-high
• Fasting blood glucose-high
• CK-high
• Sodium-low
• Coeliac-ddx
• Antithyroid peroxidase antibodies-high

Question 10

I-third line?

Answer 10

US of neck

Question 11

M o/s first line?

Answer 11

• Levothyroxine
• Lower dose if >60 or CAD
• Increased dose if preg, renal or GI impairment
• Restores euthyroid state
• Monitor TSH 4-6 weeks after initiation
High-need to increase dose as currently too low

Question 12

M o/s second line?

Answer 12

• Refer to endocrinologist/ED if complications or CI eg pregnant, drug treatment

Question 13

Prognosis?

Answer 13

• Excellent with full recovery as soon as hormones are replaced
• Dose of thyroxine may be changed-can be controlled well

Question 14

Complications?

Answer 14

• Angina
• Resistant hypothyroidism
• AF
• Osteoporosis
• Myxoedema coma
• Preg complications