Plasma urea, creatinine and uric acid concentrations in relation to feeding in peregrine falcons (Falco peregrinus).

Significant post-prandial increases in plasma uric acid and plasma urea concentrations were observed in peregrine falcons. Post-prandial uric acid concentrations were similar to those in birds suffering from hyperuricaemia and gout and were well above the theoretical limit of solubility of sodium urate in plasma. It is not clear why under normal circumstances no urate deposits occur in peregrine falcons (and probably other raptorial birds), which show hyperuricaemia for at least 12 h after ingesting a natural meal. It is important to evaluate renal function in peregrine falcons (and perhaps other birds) after a 24-h fast to avoid misinterpretation due to physiological food-induced elevated concentrations of nonprotein nitrogen substances.