Co-occurrence of nephrocalcinosis and nephrolithiasis in feline kidneys

Nephrocalcinosis is common in cats with nephrolithiasis. Understanding the association between these disorders might facilitate understanding of their pathogenesis.

Nephrocalcinosis is associated with nephrolithiasis.

Kidneys were evaluated postmortem in 175 client-owned cats.

An observational cross-sectional study. High-resolution microradiography identified nephroliths and classified parenchymal mineralization as striated or punctate. Percentage mineralization was quantified on microradiographs. Associations of nephrocalcinosis and nephrolithiasis at cat level (disease in either the left or right kidney) and individual kidney level were estimated using chi-squared tests and logistic regression with odds ratios (ORs) and 95% confidence intervals (CIs).

Nephrolithiasis was present in 54% of cats (95/175) and nephrocalcinosis in 84% (147/175). Cats with nephroliths were older than those without (median, 15 vs 13 years; P = .004). At the cat level, nephrocalcinosis was associated with higher odds of nephrolithiasis (OR, 3.5; 95% CI, 1.6-7.4; P = .002), but the association was attenuated after age adjustment (OR, 3.1; 95% CI, 1.0-10.1; P = .05; n = 115). At the kidney level, striated mineralization was associated with nephrolithiasis (OR, 13.9; 95% CI, 2.0-95.9; P = .01), whereas punctate mineralization was not significantly associated with nephrolithiasis. Percentage mineralization was higher in cats with nephroliths than in those without it (P = .004).

Nephrocalcinosis, particularly striated medullopapillary patterns, was associated with nephrolithiasis in cats. Pattern-specific mineralization may represent a preventive target for the management of nephrolithiasis.