Dent Disease — ESENeph MCQ

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HardTubular DisordersDent DiseaseESENeph

A euvolaemic patient has sodium 118 mmol/L, serum osmolality 255 mOsm/kg, urine osmolality 520 mOsm/kg and urine sodium 45 mmol/L. Cortisol and thyroid function are normal. What is the leading diagnosis?

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Correct answer: B — Syndrome of inappropriate antidiuresis

The best answer is “Syndrome of inappropriate antidiuresis”. Hypotonic hyponatraemia with inappropriate urine concentration and sodium excretion in a clinically euvolaemic patient fits SIAD only after endocrine, renal, medicine and volume causes are excluded. “Primary polydipsia” is less appropriate because urine should be maximally dilute rather than concentrated “Cerebral salt wasting” is less appropriate because that produces clinical volume depletion “Primary adrenal insufficiency” is less appropriate because cortisol assessment is normal “Severe hypothyroidism” is less appropriate because thyroid function is normal

Reference: European clinical practice guideline on hyponatraemia: https://academic.oup.com/ejendo/article/170/3/G1/6668028