Urine Red Blood Cells (Haematuria)

When high

If Elevated (3 or more red cells/hpf):

• First rule out transient and benign causes: strenuous exercise within 48-72h, recent trauma, menstruation, vigorous sexual activity, or a urinary tract infection
• Retest on a rest day with normal hydration and a clean-catch midstream sample before pursuing investigation
• Persistent microscopic haematuria confirmed on repeat testing needs medical evaluation (urinalysis with microscopy, blood pressure, eGFR, ACR, and imaging or cystoscopy based on risk)

Key Context for Athletes:

• Exercise-induced haematuria is common and benign; it should clear within 72h of rest, so a follow-up sample is essential before alarm
• If the dipstick is positive for blood but microscopy shows few or no red cells, suspect myoglobinuria (rhabdomyolysis): check creatine kinase urgently, hydrate, and seek care if CK is markedly elevated or urine is tea-coloured
• Painless persistent haematuria in older athletes (especially smokers) requires urological work-up to exclude malignancy: do not dismiss it as training-related

When low

If Low or Absent:

• A low or zero red cell count is the normal, healthy finding and requires no action
• It helps exclude bleeding from the kidney or urinary tract as a cause of other findings

Clinical context:

• Microscopic haematuria is defined by red cells on microscopy, NOT by a dipstick alone: a positive blood dipstick must be confirmed by microscopy because myoglobin and free haemoglobin also turn the pad positive
• Dysmorphic red cells and red cell casts suggest a glomerular (kidney) source; isolated normal-shaped red cells suggest a lower urinary tract source
• Always interpret alongside the Urine Blood (Hb) dipstick, creatine kinase, and clinical context (training load, trauma, infection)