Hypothyroidism - Diagnosis and Management Summary
Signs/Sx: ...

Hypothyroidism - Diagnosis and Management Summary

Signs/Sx: Fatigue, cold intolerance, ↑ weight, constipation, dyspnea, dry skin, myalgias, abnl menses, cognitive dysfunction, depression, carpal tunnel, bradycardia, diastolic HTN, delayed relaxation of DTRs, lateral eyebrow thinning, non-pitting edema, macroglossia, froggy voice

Labs: ↑ LDL, ↑ triglycerides, ↓ Hgb (↓ MCV), ↑ CPK, ↓ Na  (*If subclinical, send TPO ab)

    Primary TSH High, FT4 Low

    Secondary TSH Low/normal, FT4 Low

    Subclinical* TSH High, FT4 Normal

Differential Dx:

 1°: Hashimoto’s (most common, +TPO ab), infiltrative dz (hemochromatosis, sarcoid), transient thyroiditis (lymphocytic, granulomatous, postpartum), drugs (lithium, amio, TKIs, contrast), iatrogenic (thyroidectomy, radiation), iodine deficiency

 2°: see Hypopituitarism section

↑ T4 requirement: pregnancy, estrogen (↑ THBG), weight gain, malabsorptive states (e.g., celiac dz), nephrotic syndrome (↑ excretion), rifampin, phenytoin, carbamazepine, phenobarbital


 - Levothyroxine (T4): starting dose ~1.6 mcg/kg/d PO (use 25-50 mcg QD for elderly or comorbidities); IV = 50-75% PO

 - Take on empty stomach 1h before eating/meds; several hrs apart from PPI, aluminum hydroxide, iron, cholestyramine

 - Check TSH q6wks and adjust dose by 12-25 mcg until normal TSH achieved

#Hypothyroidism #Diagnosis #Management #endocrinology #treatment
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