QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Hsu, J. M. Articles by Kepford, G. Search for Related Content PubMed PubMed Citation Articles by Hsu, J. M. Articles by Kepford, G.

The Effect of Magnesium Depletion on Thyroid Function in Rats¹

Jeng M. Hsu, A. W. Root^*, G. E. Duckett^*, J. Cecil Smith, Jr., A. A. Yunice and G. Kepford

Veterans Administration Medical Center, Bay Pines, FL 33504 ^* All Children's Hospital, St. Petersburg, FL 33701 Vitamin and Mineral Nutrition Laboratory, U.S. Department of Agriculture, Beltsville, MD 20705 VA Medical Center, Oklahoma City, OK 73104

The effects of dietary magnesium (Mg) depletion on thyroid function were studied in young male rats. The rats were fed a semipurified diet containing either 12 ppm Mg (deficient rats) or 662 ppm Mg (control rats) for 14 to 28 days. Results showed that the Mg-deficient rats had decreased body weight gain, lowered concentrations of plasma thyroxine (T₄) and Mg, but increased weight of the thyroid gland when expressed in proportion to the body weight (milligrams/100 g). There was no difference in the accumulation (uptake) of ¹³¹I, 24 hours after Na¹³¹I injection, between the Mg-deficient and Mg-supplemented rats. The protein-bound ¹³¹I (PB¹³¹I) level and the ratio of PB¹³¹I to total ¹³¹I in plasma was significantly reduced in Mg-deficient rats. Serum thyroid-stimulating hormone (TSH) levels after thyrotropin-releasing hormone injection (TRH, 50 ng/100 g body weight) increased fivefold at 30 minutes, but declined to near the basal level at 2 hours in both groups. No consistent difference in TSH response was observed between the two treatments. Serum T₄ response to TRH challenge was significantly reduced in Mg-deficient as compared to Mg-adequate rats at all time intervals. The reduction of T₄ level could be due to an impaired T₄ synthesis or release in Mg-deficient rats.

KEY WORDS: • magnesium • thyroid function • thyroxine • triiodothyronine

¹ Supported by the Veterans Administration and Hoffmann-LaRoche, Nutley, NJ.

Manuscript received 6 February 1984.