Abstract
Inorganic sulfate is essential for normal cellular function and its homeostasis is primarily regulated in the kidneys. However, little is known about renal sulfate handling in humans and particularly in populations with impaired kidney function such as renal transplant recipients (RTR). Hence, we aimed to assess sulfate reabsorption in kidney donors and RTR. Plasma and urinary sulfate were determined in 671 RTR and in 251 kidney donors. Tubular sulfate reabsorption (TSR) was defined as filtered load minus sulfate excretion and fractional sulfate reabsorption (FSR) was defined as 1‐fractional excretion. Linear regression analyses were employed to explore associations of FSR with baseline parameters and to identify the determinants of FSR in RTR. Compared to kidney donors, RTR had significantly lower TSR (15.2 [11.2–19.5] vs. 20.3 [16.7–26.3] μmol/min), and lower FSR (0.56 [0.48–0.64] vs. 0.64 [0.57–0.69]) (all P < 0.001). Kidney donation reduced both TSR and FSR by circa 50% and 25% respectively (both P < 0.001). In RTR and donors, both TSR and FSR associated positively with renal function. In RTR, FSR was independently associated with urinary thiosulfate (β = −0.18; P = 0.002), growth hormone (β = 0.12; P = 0.007), the intakes of alcohol (β = −0.14; P = 0.002), methionine (β = −0.34; P < 0.001), cysteine (β = −0.41; P < 0.001), and vitamin D (β = −0.14; P = 0.009). In conclusion, TSR and FSR are lower in RTR compared to kidney donors and both associated with renal function. Additionally, FSR is determined by various dietary and metabolic factors. Future research should determine the mechanisms behind sulfate handling in humans and the prognostic value of renal sulfate reabsorption in RTR.
Highlights
Inorganic sulfate is the fourth most abundant anion in human plasma, and its concentration is primarily determined by renal excretion and reabsorption (Goudsmit et al 1939; Hierholzer et al 1960)
Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society
Renal Sulfate Handling in Humans the key regulatory processes of renal sulfate handling have been extensively studied in animals and cell lines (Renfro and Dickman 1980; Leyh et al 1992; Cherest et al 1997; Smith et al 2000), very little is known about these mechanisms in humans
Summary
Inorganic sulfate is the fourth most abundant anion in human plasma, and its concentration is primarily determined by renal excretion and reabsorption (Goudsmit et al 1939; Hierholzer et al 1960). Renal Sulfate Handling in Humans the key regulatory processes of renal sulfate handling have been extensively studied in animals and cell lines (Renfro and Dickman 1980; Leyh et al 1992; Cherest et al 1997; Smith et al 2000), very little is known about these mechanisms in humans. Factors that have been shown to influence tubular sulfate reabsorption in animals and cell lines, for example, growth hormones, thyroid hormone, and nonhormonal factors, for example, dietary sulfate, vitamin, and NSAID intake, have not been assessed in humans (Sabry et al 1965; Frick and Durasin 1986; Neiberger 1991; Tenenhouse et al 1991; Fernandes et al 1997; Sagawa et al 1998a,b, 1999a,b; Markovich et al 1999)
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