Urine

Notes

Persistent non visible haematuria = referral for cystoscopy ?bladder ca (NICE)/ pastest

Investigations 

• Core

  • • • Urinalysis

      • Urine culture & microscopy

      • Urine volume production/ hour

• Rarer

  • • • Urine drug screen

      • Streph pneumonia urinary antigen

      • Legionella urinary antigen

      • 24hrly urine catecholaemines

      • 24hrly urine cortisol

      • 24hrly urine copper

      • 24hrly urine protein, albumin/ creatinine ratio

Procedures

• Catheterisation

  • Male

  • Female

Urinalysis

Features

• Blood

• Protein

• Glucose

• Leukocytes

• Nitrates

• Ketones

• Specific Gravity

Haemoproteinuria

Causes

• Glomerulosclerosis

  • Vasculitis

    • EGPA (Eosinophilic Granulomatosis with Polyangiitis) , GPA 

    • Goodpasture's Disease 

  • Diabetic nephropathy

• Nephritic Syndrome

  • IgA Nephropathy 

Haematuria

• Can be visible or non visible

Causes

• Old Age

• Urinary Cancer: Renal Cancer , Bladder cancer- high specificity, low sensitivity

• Urinary Tract Infections , Pyelonephritis - haemorrhagic cystitis

• Urinary Stones - high specificity, low sensitivity

Proteinuria

Causes

• Old Age

• Urinary Tract Infections 

Nitrates

Causes

• Old Age

• Urinary Tract Infections 

Leukocytes

Causes

• Old Age

• Urinary Tract Infections 

Ketones

Ketones are produced during starvation. Causes acidosis with a high anion gap

• Diabetes Ketotic Acidosis (DKA) 

• Alcohol Abuse

• Starvation

Glucose

Causes

• Diabetes Mellitus 

Specific Gravity

Markers of osmolality

• Raised specific gravity (high osmolality)- dehydration, Sepsis 

• Lower specific gravity (low osmolality)- Diabetes Insipidus (compared to blood)

Urine Culture, Sensitivity & Microscopy

Microscopy

Results ready < 24hrs (before sensitivities) and can give indication of UTI

Squamous Cells

• Marker of contamination

• If raised, results interpretted with caution

White Cells

• Marker of immune response

• Raised WCC specific for UTI

Red Cells

• Marker of haematuria (as discussed above)

Culture & Sensitivity

• Grow responsible organism for Urinary Tract Infection 

• Advise antibiotic sensitivities

• Often takes 24-72hrs for results to come back

• Urine culture BEFORE antibiotics is sensitive to detect an Urinary Tract Infection 

Urine Volume

• Urine production can be an excellent marker of end organ perfusion in assessing hypotension

• Aim 0.5ml/kg/hr: e.g. 30-50mls/hr or 2L per 24hrs

Oliguria 

Definition: minimal urine output, < 0.5ml/kg/hr

Concerning for an AKI

• Causes & Management

  • Pre- renal 

    • Dry: IVF

    • Overloaded: IV Furosemide

    • Poor end organ perfusion: vasopressors in HDU

  • Renal - Acute Tubular Necrosis 

  • Post renal - Benign Prostatic Hypertrophy 

Anuria 

Definition: nil urine output

Concerning for an obstruction or severe AKI

• Causes & management (in addition to oliguira causes)

  • Catheter obstruction- flush/ re-insert

  • Urinary Stones 

Assorted Urine Tests

Urine Drug Screen

Indications: concerns of toxicology cause of presentation

Detection includes benzodiazepine

Urinary Pneumonia Antigens

Detect: streptococcal pneumonia or legionella pneumonia

Indications: consolidation observed on chest XR

Metabolic Screening

24hrly urine catecholaemines: Phaeochromocytoma (raised)

24hrly urine cortisol: Cushing's Syndrome (raised)

24hrly urine copper: Wilson's Disease (raised)

24hrly urine protein, albumin/ creatinine ratio: Diabetic Mellitus Nephropathy (raised)

Med Reg Notes

• Urine isn't effective for Jelly Fish Stings

• Recurrent urine infections consider bladder cancer

Resources and References

Written in 2025