Siener R, et al. - Researchers studied the metabolic characteristics in patients with primary hyperoxaluria (PH) under controlled, standardized conditions in this pilot study. They also determined the influence of diet in the same patients. Collection of 24 h urines on the habitual, self-selected diets as well as on day 1, 6, 7, 8, and 11 under controlled, standardized conditions, was carried out by patients with genetically confirmed PH. Also, [¹³C₂]oxalate absorption, calcium, and ammonium chloride loading tests were conducted. Based on the findings, a possible benefit of dietary restriction of oxalate and hydroxyproline intake in patients with PH was suggested.