There is a high prevalence of vitamin B12 in cats with spontaneous hyperthyroidism. - GreenMedInfo Summary
The prevalence of hypocobalaminaemia in cats with spontaneous hyperthyroidism.
J Small Anim Pract. 2011 Feb;52(2):101-6. PMID: 21265849
Department of Small Animal Clinical Sciences GI Laboratory, Texas A&M College of Veterinary Medicine, College Station, TX 77843, USA.
OBJECTIVES: To determine the prevalence of hypocobalaminaemia in cats with moderate to severe hyperthyroidism and to investigate the relationship between cobalamin status and selected haematologic parameters. Methods: Serum cobalamin concentrations were measured in 76 spontaneously hyperthyroid cats [serum thyroxine (T(4) ) concentration≥100 nmol/L] and 100 geriatric euthyroid cats. Erythrocyte and neutrophil counts in hyperthyroid cats with hypocobalaminaemia were compared with those in hyperthyroid cats with adequate serum cobalamin concentrations (≥290 ng/L).
RESULTS: The median cobalamin concentration in hyperthyroid cats was lower than the control group (409 versus 672 ng/L; P=0·0040). In addition, 40·8% of hyperthyroid cats had subnormal serum cobalamin concentrations compared with 25% of controls (P=0·0336). Weak negative correlation (coefficient: -0·3281) was demonstrated between serum cobalamin and T(4) concentrations in the hyperthyroid population, and the mediancobalamin concentration was lower in cats with T(4) above the median of 153 nmol/L compared with cats with T(4) below this value (P=0·0281). Hypocobalaminaemia was not associated with neutropenia or anaemia in hyperthyroid cats.
CLINICAL SIGNIFICANCE: This study indicates that a substantial proportion of cats with T(4)≥100 nmol/L are hypocobalaminaemic and suggests that hyperthyroidism directly or indirectly affects cobalamin uptake, excretion or utilisation in this species.