5. Hypothyroidism
 Definition
 Causes of hypothyroidism
 Clinical manifestations of hypothyroidism
 Laboratory evaluation
 Autoimmune hypothyroidism

6. Definition
 The thyroid gland produce 2 related hormones,
thyroxine (T4) and triiodothyronine(T3)
 These hormones help to maintain thermogenic and
metabolic homeostasis in the adult.
 Hypothyroidism results specially from glandular
destruction and underproduction of thyroid
hormones.

7. Causes of hypothyroidism
Primary hypothyroidism:
 Autoimmune hypothyroidism: hashimoto’s thyroiditis
 Iatrogenic: radioactive iodine trt, total thyroidectomy,
external irradiation
 Drugs: amiodarone, lithium, antithyroid drugs
 Congenital hypothyroidism: absent thyroid gland,
TSH Rc mutation
 Iodine deficiency
 Infiltrative disorders: amyloidosis, sarcoidosis,
hemochromatosis…

9. Causes of hypothyroidism
Transient hypothyroidism:
Silent thyroiditis , including postpartum thyroidtis
Subacute thyroiditis
Withdrawal of thyroxine trt

10. Causes of hypothyroidism
Secondary hypothyroidism:
Hypopituitarism: tumors, pituitary surgery or
irradiation, infiltrative disorders, Sheehan’s syndrome,
trauma
Hypothalamic disease: tumors, trauma, infiltrative
disorders , idiopathic

11. Clinical manifestations
Symptoms:
 Tiredness, weakness
 Dry skin
 Feeling cold
 Hair loss
 Difficulty concentrating and poor memory
 Constipation
 Weight gain
 Dyspnea
 Hoarse voice
 Dysmenorrhea
 Paresthesias

12. Signs:
 Dry skin and cool peripheral extremities
 Puffy face, hands and feet (myxedema)
 Diffuse alopecia
 Bradycardia
 Delayed tendon reflex relaxation
 Carpal tunnel syndrome

14. Laboratory evaluation
 Dyslipidemia with elevated cholesterol and
triglycerides
 Anemia
 TSH ↑ and FT4 nle: subclinical hypothyroidism
 TSH ↑ and FT4↓:clinical hypothyroidism
 TSH nle or ↓ and FT4 ↓:secondary hypothyroidism

15. Autoimmune hypothyroidism
 Autoimmune hypothyroidism may be associated with
a goiter (Hashimoto’s disease) or ,at the later stages of
the disease, minimal residual thyroid tissue (atrophic
thyroiditis)
 First preceded by subclinical hypothyroidism with
normal thyroid hormones levels and elevated TSH
 Later ,FT4 levels fall and TSH levels rise further
 Female >male
 Anti TPO +++