Nocturia in adults

In the practice

• Urine dipstick (glycosuria, haematuria, leucocyturia)
• 72-hour voiding diary: bedtime and waking time, each void with its volume, first morning void, fluid intake.

Laboratory tests

• Fasting plasma glucose
• Serum creatinine with eGFR
• Serum calcium
• HbA1c (known diabetic)if neededKnown diabetes: poorly controlled diabetes causes 24-hour polyuria and nocturia ^[2,3]; HbA1c is reimbursed only for monitoring glycaemic control ^[4].
• Urine microscopy and culture (if dipstick positive)if neededDipstick positive for leucocytes or blood: looking for leucocyturia or haematuria is part of the tests for voiding disorders ^[2].
• Serum electrolytes (serum sodium) (if 24-hour polyuria, or before desmopressin)if needednon-French guideline24-hour polyuria (> 40 mL/kg) or planned desmopressin: serum sodium is among the tests to do according to clinical judgement, and it conditions desmopressin (no prescription if ≤ 130 mmol/L) ^[5].
• TSH (if signs of thyroid dysfunction)if needednon-French guidelineSigns of hyperthyroidism or profound hypothyroidism, which can increase urine volume ^[3]. The British primary care consensus documents (endocrine and neurological diseases) propose renal function, TSH, serum calcium and plasma glucose or HbA1c ^[3,6].
• Serum ferritin (if restless legs syndrome or periodic limb movements suspected)if needednon-French guidelineNocturnal awakenings from restless legs syndrome: iron deficiency or a ferritin below 50-75 µg/L is looked for and treated (cause to be sought, iron supplementation if needed) ^[7].
• NT-proBNP (if heart failure suspected)if needednon-French guidelineOedema, jugular venous distension or history suggestive of heart disease: heart failure is a cause of nocturnal polyuria; NT-proBNP, ECG and blood pressure, echocardiography if NT-proBNP is raised ^[8].
• Urine osmolality on morning urine, without drinking after 22 h (if persistent polyuria > 2.5 L/24 h)if needednon-French guidelinePolyuria above 2.5 L per 24 hours that persists despite fluid advice: a urine osmolality > 600 mOsm/kg on waking, with no fluids since 22 h and a normal serum sodium, rules out diabetes insipidus ^[3].

Before treatment

• Serum electrolytes (sodium)
• Serum creatinine with eGFR

Between D3 and D7

• Serum electrolytes (sodium)

At 1 month

• Serum electrolytes (sodium)