central hypothyroidism

1. CENTRAL
HYPOTHYROIDISM
BY SHUBHAM BHARDWAJ
TO TAMAR ZEREKIDZE

2. INTRODUCTION
• Central hypothyroidism is a rare and heterogeneous
disorder that is characterized by a defect in thyroid
hormone secretion in an otherwise normal thyroid
gland due to insufficient stimulation by TSH. The
disease results from the abnormal function of the
pituitary gland, the hypothalamus, or both.

4. CAUSES
• congenital(mutations of genes encoding hypothalamic and pituitary transcription
factors)
• hypothalamic lesions, pituitary tumors, breech delivery, external brain irradiation,
Sheehan’s syndrome
• many drugs (including cocaine, somatostatin analogs, glucocorticoids, dopaminergic
compounds, and bexarotene), may affect the neuroendocrine mechanisms of TSH
regulation to produce a form of CH.

5. CLINICAL MENIFESTATIONS
fatigue Depression
cold
intolerance
Short staure
dry skin constipation
bradycardia
and
hyporeflexia

6. DIAGNOSIS

7. TREATMENT
• The aim of treatment in patients with CH is to restore normal serum concentrations of circulating
thyroid hormones by administering replacement levo-thyroxine.
• Maintain the levels of serum FT4 in the middle of the normal laboratory reference range
• Reassess the dose of LT4 in a patient with combined pituitary hormone deficiency
• Monitor serum FT4 levels drawn before daily ingestion of LT4 tablets
• Treatment should be started at full-replacement doses (10-15 mg/kg of LT4) in neonates to
minimize the risk of hypothyroidism at a critical period of neurological development

8. THINGS TO CONSIDER DURING TREATMENT
• Start therapy only after the exclusion of adrenal insufficiency
• Establish the final dose based on age and sex (about 1.4-1.7 mg/kg bw) of the patient
• Suspect undertreatment when TSH levels are >0.2 mU/L
• In iodine-deficient countries, consider the possible presence of a nodular goiter with
autonomous thyroid hormone secretion in order to prevent possible LT4 overtreatment