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Light Microscopy of Indinavir Urinary Crystals
- Raymonde F. Gagnon, MD;
- Christos M. Tsoukas, MD; and
- Andrew K. Watters, MD
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TO THE EDITOR:
We read with interest the article by Kopp and colleagues [1]. The authors clearly show that indinavir, a protease inhibitor widely used in the treatment of HIV infection, forms distinctive urinary crystals.
Indinavir is metabolized largely by the liver, but up to 10% of the compound is excreted intact in the urine [2]. The drug is generally well tolerated except for the formation of renal calculi, which has been reported with a frequency of 4% to 12% [3]. In a recent study [4], urinary calculi that were recovered from 29 patients with HIV infection consisted primarily of indinavir monohydrate and contained needle-shaped crystals. In the single reported case of indinavir nephropathy [5], needle-shaped crystals were noted in the collecting ducts on renal biopsy.
In their article, Kopp and colleagues documented crystalluria in 20% of indinavir-treated patients, usually asymptomatic patients but also some with a spectrum of urologic disorders. They present five photographs showing the microscopic appearance of indinavir crystals under polarized light but none taken with regular brightfield microscopy. For this reason, we wish to report the findings of our examination of more than 200 urinary sediments from similarly treated patients with HIV infection.
Indinavir crystals appear as colorless, polarizable, pointed needles. They may occur singly but most often are grouped in various formations, such as rosettes, fans, and starbursts. In our experience, the needles are frequently arranged in rectangular plates and sheaves (Figure 1); these distinctive groupings vary greatly in size, and large forms are common.
Although the clinical significance of the crystalluria remains to be determined, we believe that physicians managing patients with HIV infection should be aware of the presence of crystalluria in those receiving indinavir and of the distinctive appearance and nature of the crystals on routine light microscopy.
Raymonde F. Gagnon, MD
Christos M. Tsoukas, MD
Andrew K. Watters, MD
Montreal General Hospital; Montreal, Quebec H3G 1A4, Canada
The Editors welcome submissions for possible publication in the Letters section. Authors of letters should:
•Include no more than 300 words of text, three authors, and five references
•Type with double-spacing
•Send three copies of the letter, an authors' form signed by all authors, and a cover letter describing any conflicts of interest related to the contents of the letter.
Letters commenting on an Annals article will be considered if they are received within 6 weeks of the time the article was published. Only some of the letters received can be published. Published letters are edited and may be shortened; tables and figures are included only selectively. Authors will be notified that the letter has been received. If the letter is selected for publication, the author will be notified about 3 weeks before the publication date. Unpublished letters cannot be returned.
Annals welcomes electronically submitted letters.
- Copyright ©2004 by the American College of Physicians
