nocturia

DEFINITION of nocturia

nocturia is waking one or more times nightly from sleep to void, disrupting normal sleep cycles. nocturia (nocturnal urinary frequency) is the complaint of waking ≥1 time per night to urinate, where sleep precedes and follows the voiding episode; affects >50% adults >50yo, multifactorial via nocturnal polyuria (>20-33% 24hr urine at night), global polyuria (>40mL/kg/day), reduced nocturnal bladder capacity, or sleep disorders; leads to fatigue, falls (25% nocturnal fractures), cognitive impairment.

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ETYMOLOGY of nocturia

latin • Noct-: Latin nox, noctis = “night.” • -uria: Greek ouron (οὖρον) = “urine.” • Literal: “Nighttime urination” (coined 19th century).

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DERIVATIONS of nocturia

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Query functionality

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Coding Context

ICD-10-CM:

Code	Description
R35.1	nocturia (primary code).
N39.41	Urge incontinence (OAB-associated).
R32	Unspecified urinary incontinence.

Associated diagnoses:

• E11.9 (DM), I50.9 (CHF), G47.33 (sleep apnea).[11]

Causes and Pathophysiology

Etiology	Mechanism/Details
Nocturnal polyuria (>33% nighttime urine)	Reduced vasopressin, leg edema mobilization, diuretics.[3][5]
Global polyuria	DM, DI, excess evening fluids/caffeine/alcohol.[1]
Bladder storage	OAB, BPH, stones, neurogenic (MS, stroke).[2]
Sleep disorders	Apnea (50% prevalence), insomnia.[5]

Related Terms

• Polyuria: >3L/24hr total.
• Nocturnal polyuria index (NPI): Night urine/24hr urine (>33% abnormal).
• OAB (Overactive Bladder): Urgency w/nocturia (N39.41).[8]
• IPSS: Symptom score includes nocturia Q.[3]

Diagnostic workup:

• Voiding diary (3 days).
• Urine/serum osmolality, A1c, BNP, PSA.
• Post-void residual (PVR), uroflow.[3]

Clinical Details

Severity:

• Mild: 1x/night.
• Moderate: 2x.
• Severe: ≥3x (odds ratio 2.5 for fractures).[3]

Risks: Falls (doubles ≥2x/night), sleep deprivation, HTN, mortality.[3]

Management:

• Lifestyle: Elevate legs PM, limit evening fluids/salt, compressions.
• Meds: Desmopressin (polyuria), anticholinergics/Mirabegron (OAB), alpha-blockers (BPH).
• Treat cause: CPAP (apnea), glycemic control.[1][2]

One-Sentence Summary
Nocturia (R35.1), Latin/Greek “night-urine,” disrupts sleep via polyuria/OAB/apnea (≥2x/night severe), doubling fall/fracture risk in elderly; diagnose via voiding diary, treat underlying etiology.[5][2][1][3]

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