CURRENT Essentials of Critical Care.pdf

Chapter 12 Endocrine Problems 185■■■Sick Euthyroid SyndromeEssentials of Diagnosis• Low T 3 in clinically euthyroid patients with acute or chronicnonthyroidal illness; reverse T 3 may be increased; free T4 almostalways normal; can be reduced in prolonged severe illness• Normal TSH indicate “euthyroid state”• TSH 20 U/mL in sick individuals suggestive of primary hypothyroidism• TSH 0.1 U/mL may be hyperthyroidism or sick euthyroidsyndrome; differentiate by thyrotropin-releasing hormone stimulationtest: sick euthyroid patients show detectable responsesof TSH, hyperthyroid have absent response• Very common; may affect up to 70% of hospitalized patients;complex, multifaceted response of endocrine system to illness• Medications may affect thyroid function: dopamine, high-dosecorticosteroids, and octreotide suppress TSH secretion; amiodaroneresults in low T 3 and normal or elevated T 4 ; propranolol,metoprolol, atenolol in large doses decrease T 3 ; rifampin increasesT 4 clearanceDifferential Diagnosis• Primary hypothyroidism • AIDS• Secondary hypothyroidism • Chronic liver disease• Diabetes mellitus • Cancer• Renal disease • Infection• Acute myocardial infarction • Surgery• Malnutrition/caloric deprivation • MedicationsTreatment• Supportive measures: adequate nutrition; specific and successfultreatment of underlying illness should result in normalizationof thyroid function abnormalities• Replacing T 3 and T 4 have not demonstrated mortality benefits;animal studies suggest increased mortality with T 3 and T 4 replacement■ PearlIn prolonged critical illness, the fall in T 3 is accompanied by a fall inT 4 and portends a poor outcome. In patients with a T 4 concentration3 g/dL mortality rates reach as high as 80%.ReferenceVasa FR et al: Endocrine problems in the chronically critically ill patient. ClinChest Med 2001;1:193. [PMID 11315456]