Gastrin-releasing peptide has a prominent role as a tumour marker in the diagnosis of small-cell lung carcinoma. This study was designed to assess the validity of a newly developed enzyme-linked immunosorbent assay (ELISA) for pro-gastrin-releasing peptide in patients with renal and systemic diseases.
Pro-gastrin-releasing peptide concentrations in sera from normal subjects and patients with small-cell lung carcinoma, diabetes mellitus, rheumatoid arthritis, systemic lupus erythematosus, chronic glomerulonephritis, or undialysed or dialysed chronic renal failure were measured with the TND-4 Kit, a newly developed ELISA for pro-gastrin-releasing peptide.
All of the patients with normal renal function, whether they had diabetes mellitus (n=16), rheumatoid arthritis (n=10), systemic lupus erythematosus (n=12) or chronic glomerulonephritis (n=14), had serum pro-gastrin-releasing peptide concentrations less than 46 ng/l, the upper limit in normal subjects. In contrast, 14 or 16 patients (88%) with small-cell lung carcinoma, who had normal renal function, and 25 of 26 (96%) patients with chronic renal failure on haemodialysis had serum pro-gastrin-releasing peptide concentrations greater than 46 ng/l. The highest serum pro-gastrin-releasing peptide levels in patients with chronic renal failure, before and after initiating haemodialysis were 183 and 290 ng/l respectively. Ten of 16 (63%) small-cell lung carcinoma patients had serum pro-gastrin-releasing peptide concentrations greater than 290 ng/l, the highest level in haemodialysed patients. Serum pro-gastrin-releasing peptide concentrations were also elevated in patients with chronic glomerulonephritis or diabetes mellitus when their serum creatinine concentrations were greater than 120 micromol/l. And, there was a significant correlation, y=23.5+0.15x(n=22, r=0.82, P<0.001),between serum pro-gastrin-releasing peptide (y, in ng/l) and serum creatine (x in micromol/l) concentrations in those patients with renal dysfunction. The correlation between serum pro-gastrin-releasing peptide and serum urea nitrogen concentrations was likewise significant.
The evaluation of patients as to their renal functional state may be mandatory when serum pro-gastrin-releasing peptide levels are to be applied as one of the diagnostic tools for small-cell lung carcinoma or as a marker monitoring their clinical course.