The maximal tubular reabsorption of phosphate in relation to serum parathyroid hormone

The relation between the renal handling of phosphate and the serum concentration of immunoreactive parathyroid hormone (i-PTH) was investigated in 15 patients with a very wide range of i-PTH, glomerular filtration rate (GFR), maximal tubular reabsorption of phosphate (TmP) and TmP/GFR-ratio. The latter was used as an index of the renal handling of phosphate. Seven patients had well functioning kidney allografts (GFR 43.1-64.9 ml/min), while 8 had varying degrees of chronic nephropathy (GFR 2.3-26.7 ml/min). The TmP, i-PTH, 51Cr EDTA clearance, the extracellular volume and serum concentrations of calcium and standard bicarbonate were estimated. An inverse significant correlation was demonstrated between TmP/GFR and i-PTH (p less than 0.001), while none of the other investigated factors correlated thyroid hormone has a key role in the regulation of the tubular handling of phosphate in patients with impaired renal function.