Objectives: To investigate whether prostaglandin D (PGD) synthase levels differ in the serum of patients with or without renal dysfunction. PGD synthase or beta-trace protein is a major constituent (approximately 3% of total protein) of human cerebrospinal fluid (CSF). We previously reported that PGD synthase levels in serum are approximately 40- to 60-fold lower than those in CSF.
Methods: We measured the PGD synthase concentration in various sera with a highly sensitive and specific immunofluorometric assay along with the serum creatinine level. Analysis for PGD synthase and creatinine was performed in 30 sera from non-renal failure subjects, in 7 sera from patients treated with continuous ambulatory peritoneal dialysis, and in 34 sera that were before and after hemodialysis samples from 17 patients with renal failure.
Results: Elevated creatinine concentration was observed in patients with renal insufficiency, as expected (Mann-Whitney P < 0.0001; chi-square P < 0.0001 ). We found that serum PGD synthase concentration from patients with renal failure is significantly elevated compared with the serum PGD synthase concentration from non-renal failure subjects (Mann-Whitney P < 0.0001; chi-square P < 0.0001). Approximately a 35-fold increase of serum PGD synthase is observed for patients with renal failure compared with non-renal failure subjects. Serum PGD synthase concentration is not affected by hemodialysis in acute renal failure patients (Mann-Whitney P = 0.918), unlike serum creatinine levels, which were decreased significantly after hemodialysis (Mann-Whitney P = 0.0001).
Conclusions: We conclude that renal impairment is highly associated with elevated serum PGD synthase levels. Measurement of PGD synthase in serum is a new biochemical marker of renal insufficiency.