The Renal Handling of Phosphate in Thyroid Disease

Abstract

The fasting serum phosphate level, the tubular maximal (Tm) phosphate reabsorption and the mean renal phosphate threshold were measured in 18 hyper-and six hypothyroid patients in comparison with 11 euthyroid control subjects. A significant increase of serum inorganic phosphate, phosphate Tm and of the mean renal phosphate threshold were found in hyperthyroidism. These findings suggest an increased tubular reabsorption of phosphate in hyperthyroidism. Four main possible mechanisms of such a renal handling of phosphate in thyroid disease are briefly mentioned although their acceptance needs more direct proof.

Effect of thyroid hormones on serum calcium and phosphorous

“…Our results are consistent with the research done by Indrajit Nath et al, 3 Shivleela MB et al, 9 Abdelgayoum A., 5 Mosekilde et al 14 and Manicort et al 15 As per our study, there is significant decrease in the concentration of serum calcium and phosphorous between hypothyroid patients and control group. Similar results have been found in the studies done by D. Sridevi et al, 16 Malamos et al 17 and Gamage et al 18 As per our study there is strong positive correlation of Serum T3 and T4 with Serum calcium (p value <0.05) and strong negative correlation of Serum TSH with Serum Calcium (p value <0.05) in hyperthyroidism which suggests that Serum calcium level will increase as there is increase in the severity of hyperthyroidism. There is also strong positive correlation of Serum T3 and T4 with Serum calcium and strong negative correlation of Serum TSH with Serum calcium (p value <0.05) in hypothyroidism which also suggests that as the severity of hypothyroidism increases Serum Calcium concentration decreases.…”

Stimulation by thyroid hormone of phosphate transport in primary cultured renal cells

“…Our findings, however, do not preclude the possibility that in the absence of ouabain a small increase in the Na+ gradient may have contributed to the enhancement of phosphate uptake. The present results are consistent with the action of thyroid hormone, when administered in vivo, in increasing phosphate reabsorption by the kidney (Malamos et al, 1969;Bommer et al, 1979) and in increasing phosphate uptake in brush border membrane vesicles prepared from hormone-treated animals (Espinosa et al, 1984;Kinsella and Sacktor, 1985;Yusufi et al, 1985).…”

“…Several lines of evidence suggest that thyroid hormone is an important regulator of phosphate transport in the kidney. The hormone raises the concentration of plasma phosphate and the filtered load of the anion and increases the maximum tubular capacity for phosphate reabsorption (Malamos et al, 1969;Bommer et al, 1979). These earlier physiological studies, however, do not provide direct information on the anatomic site along the nephron at which thyroid hormone acts or on the mechanism by which phosphate transport is increased.…”

Effect of block-replacement regimen on bone mineral density and biochemical markers in patients with thyrotoxic bone disease

“…Our patients had normal serum phosphorous both pre-and post-treatment. Other investigators have also reported a normal phosphorus level 43 while some others have found elevated serum phosphorus, 44,45 possibly due to suppressed parathyroid hormone and enhanced mobilization from bone and soft tissues. 10 We did not find any correlation between serum phosphorous and BMD.…”