A 40-year-old woman presented to her physician with complaints of intermittent flank pain. A urine sample was submitted for routine urinalysis. The patient's sample (left) was notable for a milky white appearance after centrifugation (Fig. 1; a normal urine sample is shown at right). The patient was born in India but moved to the US 10 years ago. She has a 5-year self-reported history of occasional cloudy urine with passage of small blood clots.

Fig. 1. A urine sample from the patient following centrifugation (left) and a normal urine sample (right).


  1. What is responsible for the milky appearance of this urine sample?
  2. How can the cause of the milky appearance be identified?
  3. Does the cause of the milky appearance interfere with urinalysis?

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