Endgames Case Review

A man with rust coloured urine and normocytic anaemia

BMJ 2015; 350 doi: https://doi.org/10.1136/bmj.h2113 (Published 01 May 2015) Cite this as: BMJ 2015;350:h2113
  1. Sarah Case, fifth year medical student1,
  2. Thomas J Johnston, National Institute for Health Research academic clinical fellow in urology2,
  3. Michael O’Sullivan, consultant cardiologist3,
  4. Will Thomas, haematology specialist registrar4,
  5. Oliver J Wiseman, consultant urologist 2
  1. 1School of Clinical Medicine, Addenbrooke’s Hospital, Cambridge CB2 0QQ, UK
  2. 2Urology Department, Addenbrooke’s Hospital
  3. 3Cardiology Department, Addenbrooke’s Hospital
  4. 4Haematology Department, Addenbrooke’s Hospital
  1. Correspondence to: T Johnston thomasjohnston1{at}nhs.net

A 65 year old man presented to the emergency department with a 10 day history of dark urine, general malaise, and progressive shortness of breath. He had a history of rheumatic heart disease and had been on warfarin since he had a metallic mitral valve replacement in 1984. He was a retired teacher, drank a minimal amount of alcohol, and was a non-smoker. He had no family history of cancer.

On examination he was jaundiced with a sinus tachycardia (120 beats/min) and a pansystolic murmur. His other vital signs were normal. On examination, his other systems were normal except for mild suprapubic tenderness, as were the results of a digital rectal examination.

His urine was rust coloured (fig 1) with no blood clots. Urine dipstick was positive for blood (3+), protein (3+), and leucocytes (3+), but negative for nitrites. No red blood cells or casts were noted during microscopy.

Fig 1 Patient’s urine on admission

The table shows the results of his initial laboratory investigations. A peripheral blood film showed red cell fragments, polychromasia, and normal platelets (a representative smear is shown in fig 2). The results of chest radiography, computed tomography of the kidneys, and ultrasound of the urinary tract were also unremarkable. Serial sepsis screens and three sets of blood cultures for endocarditis were all negative.

View this table:

Laboratory test results on admission

Fig 2 A representative blood film showing red cell fragments (arrows)

Questions

  • 1. What are the causes of dark urine?

  • 2. What are the causes of mechanical haemolytic anaemia?

  • 3. What is the most likely diagnosis in this patient?

  • 4. How would you further investigate this patient?

  • 5. How should this patient be managed?

Answers

1. What are the causes of dark urine?

Answer

Haematuria, menstrual contamination, haemoglobinuria, and myoglobinuria will cause dark urine that is positive for blood on urine dipstick testing. Red cells …

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