Total body zinc depletion and its relationship to the development of hyperprolactinemia in chronic renal insufficiency

Abstract

Modulation of free plasma zinc levels has been implicated in the increase in plasma prolactin levels seen in patients with chronic renal insufficiency (CRI). The relative importance of this mechanism in comparison to others, however, has not been elucidated. Zinc equilibrium between plasma and red blood cells is partly dependent upon red blood cell carbonic anhydrase (CA). In the present paper, we have investigated the interrelationships among total plasma zinc, leukocyte zinc, prolactin, and erythrocyte CA in patients with CRI. Uremic patients were shown to have significantly increased levels of plasma prolactin and erythrocyte CA activity when compared to normal controls. Moreover, red blood cell CA total concentration and isoenzyme-I and-II levels, as well as plasma zinc were found to be significantly decreased in uremic patients in comparison to normal controls. In patients with CRI, a negative correlation was demonstrated between erythrocyte CA catalytic activity and plasma zinc, as well as between plasma zinc and plasma prolactin levels. Moreover, leukocyte zinc content, which is a reliable indicator of total body zinc stores, was found to be significantly decreased in uremic patients when compared to normal controls. A strong negative correlation between leukocyte zinc content and plasma prolactin levels was documented in CRI patients. Our results suggest that alterations in erythrocyte CA levels, enzymatic activity or isoenzyme profile are most probably mechanistically and etiologically unrelated to the high plasma prolactin levels in CRI patients. Contrariwise, depletion of total body zinc stores, rather than redistribution of this trace metal among extracellular compartments, may represent one of the major contributing mechanisms leading to uremic hyperprolactinemia.

Prolactin Levels, Endothelial Dysfunction, and the Risk of Cardiovascular Events and Mortality in Patients with CKD

“…In CKD, prolactin levels appear substantially elevated, with a prevalence of hyperprolactinemia ranging from 30% to 65% (5)(6)(7). Hyperprolactinemia in CKD is the consequence of both reduced renal clearance (7) and increased production (8,9).…”

Gonadal dysfunction in systemic diseases

“…In these cases, imaging studies of the hypothalamic -pituitary region should be performed to exclude the presence of a microadenoma or a macroadenoma. Depletion of total body zinc stores may also play an etiologic role in uremic hyperprolactinemia (44).…”

Research on zinc blood levels and nutritional status in adolescents with autoimmune hepatitis

“…The method of atomic absorption spectrophotometry was used in both procedures, and they followed standard literature methods (2,9) . The normality value of plasma Zn used was the one adopted by the UNICAMP Teaching Hospital, varying between 80 and 120 µg/dL.…”

“…Signs and clinical symptoms of Zn deficiency include growth delay, hypogonadism, decreased appetite and hypogeusia, decreased cognitive functions, enteropathic acrodermatitis, alopecia, diarrhea, skin rash and immunodeficiency (23) . The specialized literature reports difficulty in establishing a trusted indicator to determine Zn deficiency, despite the difficulty of its method of analysis, some studies have affirmed that leukocyte Zn is the most trustworthy biomarker (2,8) .…”