NEW YORK (Reuters Health) - Kidney stones linked to melamine-tainted infant milk formula can usually be managed conservatively, Chinese authors report. For infants with renal failure, hemodialysis without surgery was usually adequate.
In August 2008, Chinese officials reported that melamine had been illegally added to some milk-based formulas to increase the protein content. Since then, several young children who drank the tainted milk have died and thousands have developed kidney stones. (See Reuters Health reports September 12 and December 2, 2008.)
In a paper scheduled for publication in the April Journal of Urology, Dr. Jian Guo Wen and colleagues at the First Affiliated Hospital of Zhengzhou University report that in their region, more than 3,000 children came for free medical evaluations after ingesting melamine-tainted formula. In 165, the researchers diagnosed melamine related urinary stones. Fifty children (mean age 23.4 months) had bilateral stones.
The children in this subgroup drank the formula for an average of roughly one year, the authors said. Thirty-one had symptoms, including altered frequency of urination, crying at urination or unexplained crying, and oliguria or anuria. Twenty-eight had mildly acidic urine (pH 6 or less), and 11 had renal failure.
Thirty-three patients had stones ranging from 4-10 mm in diameter (based on ultrasound findings); the other youngsters had smaller calculi. The stones - mainly uric acid and melamine -- were radiolucent on plain x-ray but clearly visible on CT.
Management consisted of hydration, IV sodium bicarbonate 5% to raise urine pH, and an antispasmodic drug (anisodamine 0.1-0.3 mg/kg or atropine 0.1-0.2 mg/kg) to help the stones pass.
Eight of the 11 children with renal failure received up to four sessions of hemodialysis. One patient required ureteral catheterization for a week to drain the renal pelvis.
Children remained in the hospital for an average of 8 days; by discharge, all clinical symptoms resolved. No patient died. Within a month, 33 children passed their stones; in the other 17 youngsters, the stones became smaller.
Despite the good outcomes, the authors advise that "these children need to be monitored for long-term effects of melamine-tainted mild formula consumption."
In a short editorial comment, Dr. John C. Pop at Vanderbilt Children's Hospital, Nashville, Tennessee, disagrees with using hemodialysis to treat renal failure in these children. Instead, he advocates "stenting to relieve the obstruction, followed by conservative treatment" until the stones resolve. He would reserve hemodialysis for patients whose renal insufficiency persists.
Dr. Wen's team defends its management decisions, noting that not all the hemodialysis patients had significant ureteral obstruction. "Hemodialysis was performed according to the regimen issued by the Ministry of Health," and parents of the patients opted for this treatment instead of stenting.
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