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Idiopathic nocturnal polyuria in an older man — MSRA MCQ

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ModerateUrologyIdiopathic nocturnal polyuria in an older manMSRA

A 69-year-old man has nocturia 3 to 4 times nightly despite 3 months of evening fluid and caffeine reduction. Tamsulosin has improved his previously troublesome hesitancy and weak stream; he has no urgency, urge incontinence, dysuria or recurrent UTI. A 3-day frequency-volume chart confirms nocturnal polyuria. Examination is unremarkable, post-void residual volume is 40 mL, and there is no clinical evidence of heart failure, obstructive sleep apnoea, diabetes mellitus or peripheral oedema. He takes no diuretic, SSRI, NSAID or other regular medication. eGFR is 63 mL/min/1.73 m² and serum sodium is 140 mmol/L. He wishes to try drug treatment for persistent sleep disruption. What is the most appropriate management plan?

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Correct answer: D — Prescribe desmopressin 50 micrograms sublingually nightly, limit fluid intake from 1 hour before until 8 hours after dosing, and check serum sodium in 4 to 8 days and at 1 month

This man has documented nocturnal polyuria, persisting despite conservative measures, with alternative medical causes and significant bladder outlet obstruction reasonably excluded. NICE supports considering oral desmopressin in men with nocturnal polyuria after other causes have been excluded and other treatments have not helped. The UK SmPC for Noqdirna specifies a sex-specific dose of 50 micrograms nightly for men, administered sublingually 1 hour before bedtime. In people aged 65 years or over, sodium must be normal before treatment, then rechecked in the first week (4 to 8 days) and again at 1 month because hyponatraemia risk rises with age. Fluid intake must be restricted from 1 hour before until 8 hours after administration. A uses the female dose; age alone does not change the recommended male dose to 25 micrograms. B omits essential fluid restriction and monitoring. D exceeds the recommended dose for an older man; dose escalation is not recommended in those aged 65 years or over. E incorrectly uses intermittent anticipatory dosing: the licensed regimen is once daily for symptomatic nocturia due to idiopathic nocturnal polyuria.

Reference: Lower urinary tract symptoms in men: management — Recommendations (2010) — https://www.nice.org.uk/guidance/cg97/chapter/recommendations Noqdirna 50 microgram oral lyophilisate — Summary of Product Characteristics (2026) — https://www.medicines.org.uk/emc/product/4372/smpc Noqdirna 50 microgram oral lyophilisate — Summary of Product Characteristics (2026) — https://www.medicines.org.uk/emc/product/4372/smpc