Blood on Urine Dipstick
September 10th, 2020
Overview
A urine dipstick is able to detect urinary haemoglobin (free or within red cells) as a surrogate for blood. This test also detects the presence of myoglobin.
- A positive dipstick for blood means one of three things:
- Haematuria - microscopic or macroscopic blood in the urine
- Haemoglobinuria - free haemoglobin within the urine, which is a marker of intravascular haemolysis
- Myoglobinuria - myoglobin within the urine, which is a marker of rhabdomyolysis
Causes of Positive Dipstick for Blood
Haematuria
- Glomerulonephropathy - congenital glomerulonephropathy, primary or secondary glomerulonephritis
- Vascular pathology - arteriovenous malformation, renal vein thrombosis, renal infarct
- Polycystic kidney disease
- Urinary tract infection - urethritis, cystitis, pyelonephritis, prostatitis, tuberculosis
- Neoplasm - renal, bladder, prostate
- Renal calculus
- Inflammation - interstitial cystitis
- Haemorrhagic cystitis (cyclophosphamide)
- Trauma
Haemoglobinuria
- Microangiopathic haemolytic anaemia - TTP, HUS, DIC, preeclampsia / HELLP, severe burns, brown snake bite
- Mechanical haemolysis - valvular leak, cardiac prostheses, renal replacement, ECMO, march haemoglobinuria
- Alloimmune haemolysis - transfusion reaction, haemolytic disease of the newborn
- Infection-induced haemolysis - severe malaria, Clostridium toxin
- Paroxysmal nocturnal haemoglobinuria
- G6PD deficiency
Myoglobinuria
- Immobilisation
- Strenuous exercise
- Limb ischaemia
- Trauma / exposure - severe trauma, crush injury, severe burns, electrocution, heatstroke, snake bite
- Myositis - viral, bacterial, polymyositis, dermatomyositis
- Electrolyte disturbances - hyponatraemia, hypernatraemia, hypokalaemia, hypophosphataemia, hypocalcaemia
- Drugs - statins, malignant hyperthermia, neuroleptic malignant syndrome
- Hereditary - deficiency of enzymes involved in lipid / carbohydrate / purine metabolism
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