Neutrophil function in hypothyroid patients.

We investigated whether some in vitro polymorphonuclear (PMN) granulocyte functions were impaired in patients with hypothyroidism, since this disease has previously been associated with an increased susceptibility to infectious agents and decreased leukocyte heat production. PMNs from 9 of 17 hypothyroid patients exhibited a decreased ability to kill Staph. aureus in vitro compared with euthyroid controls (p less than 0.02). This was normalized in all patients tested after therapy with levothyroxine. In 3 patients, studied repeatedly during the initial phase of therapy, PMN bactericidal capacity was gradually normalized. In addition, PMN adherence to nylon fibres showed a transient decrease approximately 6 weeks after initiation of therapy. PMN chemiluminescence during phagocytosis of Staph. aureus and stimulated and spontaneous migration under agarose were normal and did not change during therapy. Thus, the decreased bactericidal capacity found in half of these hypothyroid patients might confer an increased susceptibility to cerain infectious agents.