Kidney function of pullets and laying hens during outbreaks of urolithiasis

Renal function evaluations were conducted on pullets and laying hens during outbreaks of urolithiasis. The following parameters were measured: kidney weights; hematocrits; plasma concentrations of uric acid, calcium, inorganic phosphate, magnesium, sodium, and potassium; urine flow rates; glomerular filtration rates; renal plasma flow rates; urine pH; and relative clearances of inorganic phosphate, calcium, magnesium, sodium, potassium, and para-amino hippuric acid. The adequacy of renal portal perfusion was estimated by timed phenol red extraction. Considerable interindividual variability was noted, presumably due to differences in age and reproductive status. Intraindividual left versus right kidney comparisons also were made, since urolithiasis often is associated with macroscopic lesions of one kidney but not the other. The results indicate that even when gross lesions of only one kidney were present, specific tubular transport processes were similar in both kidneys. Urolithiasis did cause significant alterations in urine flow rates, glomerular filtration rates and renal plasma flow rates. it was concluded that the changes associated with urolithiasis reflect the expected compensatory hypertrophic responses of surviving kidney tissue to a reduction of renal mass. The physiological impact of this form of kidney damage appears to arise from reduced renal mass rather than from inappropriate renal handling of minerals or electrolytes.