Quantitative urinalysis in kittens from four to thirty weeks after birth

Abstract

Summary To evaluate renal function and obtain reference values for measurements of urinary excretion of various substances, quantitative urinalysis was performed in healthy, growing kittens from 4 to 30 weeks after birth. Endogenous creatinine clearance, 24-hour urine protein excretion, and urine protein-to-creatinine ratio were determined. Additionally, fractional excretion to creatinine clearance was calculated for calcium, inorganic phosphorus, sodium, potassium, and chloride. Mean ± SD endogenous creatinine clearance values (range, 3.80 ± 0.48 to 4.74 ± 0.61 ml/min/kg) were significantly (P < 0.0001) higher in kittens 9 to 19 weeks old, compared with younger (range, 1.39 ± 0.85 to 3.59 ± 0.86 ml/min/kg) and older kittens (range, 2.69 ± 0.40 to 3.46 ± 0.37 ml/min/kg). Mean values for all kittens for 24-hour urine protein excretion (range, 2.54 ± 1.81 mg/kg at 4 weeks to 11.39 ± 7.61 mg/kg at 14 weeks) and for urine protein-to-creatinine ratio (range, 0.14 ± 0.03 to 0.34 ± 0.18) varied from week to week of age. The urine protein-to-creatinine ratio in kittens > 9 weeks old correlated well (R2 = 0.861) with 24-hour urine protein excretion. Urinary fractional excretion of calcium, inorganic phosphorus, sodium, potassium, and chloride in kittens varied among age groups, being significantly (P < 0.01) different for potassium and calcium in young kittens (4 to 6 weeks) and older kittens (≥ 7 weeks).