Serum Growth Differentiation Factor 8 (Myostatin) Concentrations in Cats with Early-Stage Chronic Kidney Disease

Weight loss occurs with chronic kidney disease (CKD) and is present in the early stages. Growth differentiation factor 8 (GDF8), also known as myostatin, is a negative regulator of muscle growth, and circulating GDF8 concentrations are increased in people with CKD. The objective of this study was to evaluate if serum GDF8 concentrations in cats with early CKD are increased compared to healthy cats. Associations of GDF8 with age, sex, body weight, body condition score (BCS), muscle condition score (MCS), and selected renal parameters were also examined. Serum GDF8 in healthy (<i>n</i> = 10), International Renal Interest Society (IRIS) stage 1 CKD (<i>n</i> = 5), and IRIS stage 2 CKD (<i>n</i> = 10) cats was quantified using a commercially available sandwich ELISA. GDF8 was not different amongst healthy cats (2137 ± 740 pg/mL) and cats with IRIS stage 1 (1785 ± 530 pg/mL) and IRIS stage 2 (1961 ± 638 pg/mL; <i>p</i> = 0.608) CKD. GDF8 was moderately correlated with MCS (<i>r_s</i> = 0.517, 95% CI 0.006-0.814, <i>p</i> = 0.049) and inversely correlated with age (<i>r</i> = -0.429, 95% CI -0.705 to -0.041, <i>p</i> = 0.032), but no association was found with the selected renal parameters, body weight, or BCS.