Hyperthyroid Cats and the IDEXX SDMA Test for Kidney Function
Hyperthyroidism is a disease seen primarily in older cats, in which kidney disease is also common. The clinical challenge is that hyperthyroidism can mask the presence of kidney disease, and until now, there has not been a reliable routine diagnostic test that can assess kidney function in cats affected by hyperthyroidism.
Creatinine is a common test for kidney disease and is measured with a blood test. Creatinine, being a by-product of muscle, is under-produced in feline hyperthyroidism as a result of muscle loss, and thus becomes a poor indicator of kidney function in hyperthyroid cats. Creatinine is also lowered by the hyperfiltration associated with the increased metabolic state that is common in hyperthyroid cats.
IDEXX Laboratories has developed a test, the SDMA Test, which is NOT impacted by weight loss and muscle mass and appears to be only slightly blunted by hyperfiltration, making it a much more reliable marker of kidney function in hyperthyroid cats.