Renal Insufficiency and Secondary Hyperparathyroidism in Elderly Patients

Abstract

SUMMARY. Glomerular filtration rate (GFR) is frequently reduced in elder1 -Rople. However, the effect of this on mineral metabolism in this population has recr3ved little attention. GFR, serum intact parathyroid hormone (PTH) and vitamin D mdabolites , were measured in 37 patients admitted to hospital for various reasons. In 20 patier>:--wirli GFR > 50 mL/min, an elevated serum intact PTH concentration (> 5 . 4 pmol/L) was found in two, while in 17 patients with GFR < 50 mL/min PTH was elevated in 13. One of this group was hypercalcaemic and presumed to have primary hyperparathyroidism. Adjusted calcium was normal in all other patients. Two patients had a low serum 25-hydroxyvitamin D concentration (< 9 nmol/L) suggesting vitamin D insufficiency while a further five had a reduced 1,25-dihydroxyvitamin D concentration, four of these having a GFR < 50 mL/min. We conclude that hyperparathyroidism is common in hospitalized elderly patients, particularly in those with mild to moderate renal insufficiency. This may contribute to bone mineral loss in such patients. Additional key phrases: glomerular filtration rate; intact parathyroid hormone; 2s-hydroxyvitamin D; 1,2S-dihydroxyvitamin DAbnormalities of bone and mineral metabolism are an almost inevitable consequence of renal failure. Secondary hyperparathyroidism, which undoubtedly contributes to these abnormalities, occurs early in the course of chronic renal insufficiency and may result from decreased calcium absorption as a consequence of reduced renal synthesis of 1,25-dihydroxyvitamin D (1,25(OH),D). However, because of the frequent absence of specific symptoms, relatively few data have appeared on calciotropic hormone levels in patients with mild to moderate renal impairment. I Glomerular filtration rate (GFR) decreases with age2 and elderly patients may thus provide a population on whom to study biochemical markers of calcium and bone metabolism in mild renal insufficiency. Moreover, ageing itself has important effects on bone homeostasis. Everyone loses bone with ageing, though in women the rate of loss is greater than in men.' The factors responsible for the loss of cortical and trabecular bone It is well established that parathyroid hormone (PTH) is a key regulator of 1,25(OH),D synthesis which ultimately regulates calcium absorption. Responsiveness within this regulatory pathway appears to become impaired in elderly osteoporotic patient^.^ There have been reports that serum PTH levels increase with age,6s7 which could result from functional impairment of the ageing kidney or could reflect altered vitamin D metabolism.* However, previous studies have involved the use of assays of PTH which recognize carboxy-terminal hormone fragments. Though known to accumulate in renal insuffi~iency,~ such fragments are of no known biological significance and do not reflect parathyroid secretory activity. In contrast, assays recognizing the amino terminal segment of the PTH moleculelo have suitable specificity in biological terms but lack the sensitivity needed to detect sm...

Secondary Hyperparathyroidism in Patients from Western Australia with Hip Fracture: Relationship to Type of Hip Fracture, Renal Function, and Vitamin D Deficiency

“…There were patients with secondary HPTH who had vitamin D deficiency and relatively normal renal function and patients with secondary HPTH caused by renal insufficiency who had normal vitamin D levels. These data are consistent with other studies 14–16 and suggest that secondary HPTH in older people is a heterogeneous disorder, which, in this study, was caused in about equal proportions by vitamin D deficiency and renal insufficiency. Age‐related renal disease may contribute to bone loss and fractures in older people independent of vitamin D deficiency, but this requires further study.…”

Reliability of parathyroid hormone measurements in the period immediately following hip fracture

“…Serum calcium was corrected for the albumin level. Plasma PTH was measured using a twosite assay for the intact molecule (Ciba-Corning Diagnostics, Halstead, UK) as described previously [9,10], with a reference range of 0.9-5.4 pmol/1. The inter-and intra-assay variations at 2.9 pmol/1 are 9% and 7.2% respectively, and at 39.2 pmol/1 are 5.4% and 3.4% respectively [10].…”

Vitamin D deficiency: a concern in pregnant Asian women

“…Measurement of parathyroid hormone Intact PTH was measured by immunochemiluminometric assay (Magic Lite ; Ciba Corning Diagnostics, Halstead, Essex). The adult reference range for non-pregnant individuals is 0.8-5.4 pmol/l (Turner et al 1991). However, in view of a previous study (Davis et al 1988) which showed reduced levels of PTH in pregnant women, a cut-off of 4 pmol/l was selected as the upper reference value in our investigation.…”

“…All samples that yielded high PTH had 250HD estimated by competitive-protein-binding assay following sample extraction (Medgenix Diagnostics, 6220-Fleurus, Belgium). The reference for normal adults is 8-50 ng/ml (Turner et al 1991).…”