3rd Department of Medicine, Krankenhaus der Barmherzigen Schwestern, vom Hl.Kreuz, Wels, Austria
A 51-year-old male (GC, speaking Italian only) was admitted to our hospital in Austria because of shivering, fever and dysuria for approximately 2 days. Clinical evaluation revealed no abnormal findings at physical examination. Blood pressure was 150/80 mmHg, pulse was 80 per minute and body temperature was 39.6°C. The patient denied any irregularities regarding stool.
Routine laboratory tests showed an elevated white blood cell count of 17.9 G/l and a C-reactive protein of 153 mg/l. The patient was asked to provide urine for examination and a few minutes later he brought a beaker with blue urine (Figure 1). Dipstick urine analysis revealed leukocytes +++, nitrit +, protein +, and erythrocytes +. Microscopic examination showed numerous leucocytes (Figure 2
). Renal sonography was normal.
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What is the diagnosis in this Italian tourist? Why is the urine blue? (Answer on next page).
Answers to quiz on the preceding page
Changes in colour of the urine are always impressive at least for the patients, and may be an important diagnostic sign. Most frequently, an altered colour is caused by gross haematuria with pink to red or black appearance [1]. Other changes include milky-white, pink-red-purple, red-brown-black, and blue-green [2]. Among others a blue-green urine may result from inherited metabolic disorders like the blue diaper syndrome [3], drug ingestion (e.g. amitriptyline, indometacin), or results from administration of indigo carmine or methylene blue. This latter substance is used for diagnostic purposes [4], in therapy of methemoglobinaemia [5], but also as a disinfectant due to its mild antiseptic action [6]. Methylene blue is excreted slowly, partly unchanged. Martindale lists 28 preparations containing methylene blue [6], of whom 14 are used topically for diverse eye disorders and six are given orally for urinary tract infections in a few countries of the world only (France, Germany, Italy, Spain, USA).
Our patient had no history of inherited disease. When confronted with the strange finding of a blue urine, the patient apologized not to have mentioned the medication he was taking. Because of dysuria he was prescribed Mictasol bleu® (Italian and French trademark; containing methylene blue 20 mg, malva purpurea 250 mg) thrice daily by his Italian doctor 2 weeks ago. Microscopic analysis of the urine was characteristic (Figure 2), and Escherichia coli could be grown in urine culture. A broad spectrum antibiotic was given and the patient left the clinic the next day. The diagnosis was urinary tract infection, and blue coloured urine due to ingestion of methylene blue.
There is a saying that `travelling educates', but travellers may do so too with doctors.
Notes
* The readers of our journal are encouraged to submit material for this section. Submissions should be directed to the Section Editor, Dr T. Rabelink, University Hospital, Department of Nephrology, PO Box 85500, Fo 3.226, 3508 GA Utrecht, The Netherlands.
References