Peripheral blood mononuclear cells do not reflect skeletal muscle mitochondrial function or adaptation to high-intensity interval training in healthy young men.

Measurement of skeletal muscle mitochondrial respiration requires invasive biopsy to obtain a muscle sample. Peripheral blood mononuclear cell (PBMC) mitochondrial protein content appears to reflect training status in young men; however, no studies have investigated whether there are training-induced changes in PBMC mitochondrial respiration. Therefore, we determined whether PBMC mitochondrial respiration could be used as a marker of skeletal muscle mitochondrial respiration in young healthy men and whether PBMC mitochondrial respiration responds to short-term training. Skeletal muscle and PBMC samples from 10 healthy young (18-35 yr) male participants were taken before and after a 2-wk high-intensity interval training protocol. High-resolution respirometry was used to determine mitochondrial respiration from muscle and PBMCs, and Western blotting and quantitative PCR were used to assess mitochondrial biogenesis in PBMCs. PBMC mitochondrial respiration was not correlated with muscle mitochondrial respiration at baseline ( R2 = 0.012-0.364, P > 0.05). While muscle mitochondrial respiration increased in response to training (32.1-61.5%, P < 0.05), PBMC respiration was not affected by training. Consequently, PBMCs did not predict training effect on muscle mitochondrial respiration ( R2 = 0.024-0.283, P > 0.05). Similarly, gene and protein markers of mitochondrial biogenesis did not increase in PBMCs following training. This suggests PBMC mitochondrial function does not reflect that of skeletal muscle and does not increase following short-term high-intensity training. PBMCs are therefore not a suitable biomarker for muscle mitochondrial function in young healthy men. It may be useful to study PBMC mitochondrial function as a biomarker of muscle mitochondrial function in pathological populations with different respiration capacities. NEW & NOTEWORTHY Research in primates has suggested that peripheral blood mononuclear cells (PBMCs) may provide a less-invasive alternative to a muscle biopsy for measuring muscle mitochondrial function. Furthermore, trained individuals appear to have greater mitochondrial content in PBMCs. Here we show that in healthy young men, PBMCs do not reflect skeletal muscle mitochondrial function and do not adapt in response to a training intervention that increases muscle mitochondrial function, suggesting PBMCs are a poor marker of muscle mitochondrial function in humans.

Role of octreotide on release of intact 1-84 parathyroid hormone from human parathyroid cells.

BACKGROUND: Octreotide has been shown to lower urinary calcium in primary hyperparathyroidism although the mechanism remains unclear. This study examined the effect of octreotide on parathyroid hormone (PTH) secretion from human parathyroid cells in culture and as isolated cells. Additionally in situ hybridization was performed for somatostatin receptor messenger RNA (mRNA) and immunocytochemistry for somatostatin in eight parathyroid adenomas. METHODS: Tissue from three hyperplastic glands and three adenomas was studied as dispersed cell suspensions. Incubation was in buffers containing high (2.0 mmol/l) and low (0.5 mmol/l) calcium concentrations, with or without octreotide 200 ng/ml. Cells were also seeded into tissue culture wells for 24 h to allow receptors to regenerate. Supernatant was removed at regular intervals and PTH levels were estimated using a two-site chemiluminescent assay. RESULTS: Mean(s.e.m.) PTH secretion at 90 min in hyperplastic cells was 445(75) pmol/l in low calcium and 160(42) pmol/l in high calcium (P< 0.02), and in adenoma cells was 170(21) pmol/l in low calcium and 137(27) pmol/l in high calcium (P=0.37). There was no significant difference in secretion of PTH from cells incubated with octreotide either in culture or as dispersed cells. In situ hybridization failed to demonstrate any mRNA for the somatostatin receptors and no somatostatin was detected in any cells with immunocytochemistry. CONCLUSION: Somatostatin has no direct action on PTH production and release from human parathyroid cells and is unlikely to be of any therapeutic value in the treatment of hyperparathyroidism.

Employment of a phenoxy-substituted acridinium ester as a long-lived chemiluminescent indicator of glucose oxidase activity and its application in an alkaline phosphatase amplification cascade immunoassay.

This paper describes the employment of a novel phenoxy-substituted acridinium ester (di-ortho-bromophenyl-AE) as a chemiluminescent endpoint indicator for ligand binding assays. The reactivity of this compound is such that it is capable of generating a high-intensity chemiluminescent signal at neutral pH. Under these conditions, when present in excess, it has been used as an indicator of hydrogen peroxide generation by the action of glucose oxidase (GOx, EC 1.1.3.4) on glucose substrate. The resulting chemiluminescent signal is a long-lived glow. The magnitude of the chemiluminescent signal is directly proportional to the quantity of GOx present and has been used to measure GOx with a sensitivity of 1.8 x 10(-16) mol. In addition, this ability to monitor GOx activity has been utilized in an alkaline phosphatase (ALP, EC 3.1.3.1) amplification cascade assay. Here ALP catalyzes the formation of FAD from a prosthetogenic substrate FADP. FAD, a cofactor for a number of oxidase enzymes, then converts inactive apo-GOx to holo-GOx, the activity of which is monitored by the chemiluminescent endpoint and facilitates detection of ALP over the range 10(-15) to 4.1 x 10(-19) mol. The clinical utility of this system has been demonstrated by application to the assay of human thyrotrophin (TSH, sensitivity 0.005 mU/liter).

Water immiscible solvent based immunoassay.

A competitive monoclonal antibody-based immunoassay which quantifies a hydrophobic hapten (Rx) in water immiscible solvents, obviating the need of a pre-extraction step, has been developed. Approximately linear dose response profiles of analyte, over the range 1-20 ugml-1 in the hydrophobic solvents, hexane, toluene and xylene were obtained. UV spectrophotometric analyses of Rx dosed hexane confirm the phenomenon of antibody-mediated transfer of analyte from the organic to the aqueous milieu. Preliminary data on the effect of water immiscible solvents on the immunoreactivity of a monoclonal antibody in free solution are presented. The potential industrial applications of water immiscible solvent based immunoassays are discussed.

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

AIM: As it is unclear whether parathyroid hormone (PTH) measurements performed immediately after hip fracture are reliable indicators of pre-fracture metabolic status, we set out to define how PTH levels are affected by hip fracture and its surgical repair. METHOD: In two longitudinal projects, we studied 12 patients presenting with hip fracture and eight patients undergoing elective hip replacement. PTH, calcium and 25-hydroxyvitamin D (25OHD) levels were measured on admission, 2 days and 1 week later and after recovery at least 2 months after initial admission. FINDINGS: In the subjects presenting with hip fracture, PTH levels during inpatient care were no different from those subsequently measured during the recovery period. In subjects undergoing elective hip surgery, PTH levels did not change following surgery and again remained unchanged into the recovery period. CONCLUSIONS: Measurements of PTH performed during inpatient care of those with hip fracture appear sufficiently reliable for use in assessment of metabolic status.

Proximal tubular reabsorption of growth hormone and sodium/fluid in normo- and microalbuminuric insulin-dependent diabetes mellitus.

Proximal tubular dysfunction may be implicated in the pathogenesis of diabetic nephropathy. An investigation of proximal tubular function was carried out by assessing proximal tubular sodium-reabsorption and low molecular weight protein excretion in a group of patients with type 1 diabetes mellitus. Normoalbuminuric [group A, n = 6, albumin excretion rate (AER) mean (range) 4 (0-10) micrograms/min], and microalbuminuric [group B, n = 6, AER 88 (35-198) micrograms/min] patients with type 1 diabetes were compared with matched controls. Simultaneous lithium and growth hormone (GH) clearance and urinary beta 2-microglobulin excretion were assessed. Fasting plasma glucose at the start of the study was [median (range)] 13 (10.2-15.1), 9.3 (5.9-15) and 4.1 (4.0-5.0) mmol/l in groups A, B and controls, respectively, with a mean coefficient of variation during the study of 3.9% (group A) and 5.2% (group B). There was no significant difference in plasma glucose levels between patients in groups A and B. Urinary GH excretion was raised in the patients with microalbuminuria (group B; P < 0.05), although there was no difference in serum GH clearance rate between the patient groups and controls. Urinary GH correlated with B 2-microglobulin in the diabetic subjects (r = 0.665, P < 0.05) and with the degree of microalbuminuria in group B patients (r = 1, P < 0.01). Urinary GH was also greater than 10 microU, the median value observed in the controls, in 5 of 6 (83%) patients in group A. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) measured by constant infusion of 51Cr-ethylene diamine tetra-acetic acid (EDTA) and I125-para-amino hippuric acid (PAH), respectively, showed relative hyperfiltration in the normoalbumiruric group compared with controls (P < 0.05) and group B (P < 0.05). Absolute proximal reabsorption of sodium and of water (APRNa and APRH2O) was significantly higher in group A patients (P < 0.05). Although GFR was significantly higher in group A patients, no differences were found in fractional proximal reabsorption of sodium and water (FPRNa+H2O) or end proximal delivery between the patient groups and controls. Therefore, the measurement of protein reabsorptive capacity provides a more sensitive marker of renal tubular impairment in type 1 diabetes than sodium/fluid reabsorptive capacity. In patients with microalbuminuria, both glomerular and tubular damage may coexist. Our results stress the usefulness of markers of renal tubular function in monitoring the course of diabetic nephropathy. This study also shows that assessment of GH clearance has promise as a marker of renal tubular protein reabsorptive capacity.

Effect of growth factors on growth of bovine parathyroid cells in serum-free medium.

Published work has suggested a possible role of the epidermal growth factor receptor (EGFr) in parathyroid disease. Bovine parathyroid cells (BPCs) are frequently used as a tissue model for studying parathyroid disorders. We have studied the effect of the EGFr ligands EGF and transforming growth factor alpha (TGFalpha), alone and with insulin-like growth factors IGF-I and IGF-II on BPC growth. Experiments were run in triplicate and repeated three times. Cell numbers were assessed on day 5 by colorimetric MTT assay as well as by tritiated thymidine uptake. Results show that TGFalpha alone (p < 0.05) and IGF-I and IGF-II alone (p < 0.05) significantly stimulated growth over controls (t-test). Furthermore, the combination of TGFalpha with IGF-I and IGF-II exhibited significant enhancement above that seen with IGF-I and IGF-II alone (p < 0.01). EGF did not stimulate growth over controls. EGFr may be expressed in BPCs, but TGFalpha exhibits a more potent growth stimulus than EGF. Addition of IGF-I or IGF-II to the growth medium further enhances this effect.

Effects of parathyroid hormone and 1,25(OH2)D3 on protein glycation in moderate uraemia.

Glucose intolerance in uraemia may be a consequence of secondary hyperparathyroidism. In this study fructosamine and glycated albumin have been used as markers of long-term glycaemic control in a group of pre-end-stage, non-diabetic uraemic patients with secondary hyperparathyroidism. The serum fructosamine level (mumol/100 g total protein) was significantly higher (p = 0.005) in uraemic patients (364 +/- 42) than in a group of 25 non-uraemic controls (332 +/- 27), but the content of glycated albumin did not differ (p > 0.05; 1.6 +/- 0.5 vs. 1.5 +/- 0.3%). In the uraemic patients, there was a significant relationship between serum 1,25-dihydroxycholecalciferol [1,25(OH2)D] (median 4.2, range 1.0-38 ng/l) and fructosamine (r = -0.66, p < 0.01; fructosamine = -2.76 1,25(OH2)D + 389), but not glycated albumin (r = -0.22, p > 0.1). No relationship existed between serum parathyroid hormone (median 15.4, range 7.0-55 pmol/l) and either glycated albumin or fructosamine (p > 0.1). In patients treated with oral calcitriol (0.25 microgram/day), significant reductions in serum parathyroid hormone after both 4 (p = 0.03) and 8 weeks (p = 0.02) and concomitant increases in serum 1,25(OH2)D (p < 0.02) after 8 weeks of treatment were not accompanied by any change in fructosamine, glycated albumin, total calcium, or ionized calcium (p > 0.05). Elevation of serum fructosamine in these patients is consistent with the impaired glucose tolerance of uraemia. The evidence presented supports a relationship between long-term glycaemic control and 1,25(OH2)D3, but not parathyroid hormone, in moderately uraemic patients with secondary hyperparathyroidism; however, serum fructosamine was not altered by treatment with calcitriol over an 8-week period.

Results of surgical treatment of renal hyperparathyroidism.

OBJECTIVE: To assess the outcome of parathyroidectomy for renal failure-related hyperparathyroidism. DESIGN: A retrospective analysis with a mean follow-up of 4.34 years of a case series of 67 consecutive patients with renal failure-associated hyperarathyroidism. SETTING: All patients were operated on at the University Hospital of Wales and Cardiff Royal Infirmary between October 1981 and December 1991. PATIENTS: Of the 67 consecutive patients, 35 were receiving hemodialysis and 32 had received a renal transplant. INTERVENTION: Total parathyroidectomy with autotransplantation was performed in 52 patients and subtotal parathyroidectomy was performed in 15. MAIN OUTCOME MEASURES: Symptomatic improvement after parathyroidectomy, the normalization of biochemical parameters, and the rate of recurrent hyperparathyroidism after parathyroidectomy. RESULTS: Symptomatic improvement after parathyroidectomy occurred in 81% of hemodialysis patients and in 72% of transplant patients. The best predictor for successful relief of skeletal pain after parathyroidectomy was an elevated preoperative alkaline phosphatase level. Recurrent hyperparathyroidism developed in four of 38 patients after total parathyroidectomy with autotransplantation and in one of 14 surviving patients after subtotal parathyroidectomy. All five patients with recurrent disease were hemodialysis patients (22%). CONCLUSIONS: Transplant patients usually present with less severe disease, have better normalization of biochemical parameters after parathyroidectomy, and rarely develop recurrent hyperparathyroidism compared with hemodialysis patients. Both total parathyroidectomy with autotransplantation and subtotal parathyroidectomy result in good control of renal hyperparathyroidism with excellent improvement of symptoms.

Urinary growth hormone measurements in children with renal insufficiency.

It has been reported that intrinsic renal factors could affect urinary growth hormone (UGH) measurements. We compared UGH excretion in 21 children aged 4-16 years, with various degrees of renal insufficiency, with that in 10 control subjects aged 5-13 years. We found 100- to 1000-fold elevations in UGH in children with plasma creatinine concentrations > 120 mumol/L (Group A) compared with patients with plasma creatinine concentrations < 120 mumol/L (Group B) and control subjects. UGH excretion (microU) in the three groups was as follows: group A 804-8556 (median 2649); group B 1.0-85 (median 7.5); and controls 2.6-7.3 (median 4.0). Elevated urinary beta 2-microglobulin levels (microgram) were also observed in group A patients: 875-15,400 (median 11,637) as compared with group B, 1.0-104 (median 32) and controls, 3-18.7 (median 8.0). There was no significant difference in albumin excretion between groups A and B through six patients in group B with nephrotic syndrome (NS) excreted significantly more albumin (P < 0.05) than the other 15 patients investigated. Our data show that abnormalities of renal function have a profound effect on growth hormone excretion and we suggest proximal tubular dysfunction as the causative factor. We conclude that UGH measurements do not provide a reliable means of assessment of hypothalamo-pituitary function in patients with renal insufficiency.

Urinary growth hormone measurements as a marker of renal tubular function in diabetes mellitus.

Urinary growth hormone (UGH) excretion was assessed in 44 adult subjects (10 control, 21 insulin dependent diabetics (Group I), 13 diabetics in poor glycaemic control (Group II)). UGH was markedly elevated in the diabetic population. The UGH excretion in (1) control subjects ranged from undetectable levels to 0.7 microU/h, mean 0.4, (2) Group I 73-422 microU/h, mean 250 and (3) Group II 10-5,283 microU/h, mean 705. There was a significant correlation between UGH excretion and albumin excretion rate (AER) (r = 0.38, P < 0.05) in the subjects studied although only 50% of patients had an AER of > 20 micrograms/min. A stronger correlation was observed between beta 2-microglobulin and UGH excretion (r = 0.7, P < 0.01). There was no significant change in the 6-h serum GH levels following treatment in the patients in Group II. However a 23-79% decline in UGH excretion was observed following improvement of glycaemic control, although UGH levels failed to revert to normal. We conclude that the major factor responsible for increased UGH excretion in DM appears to be reduced tubular reabsorption of the hormone. This test may therefore prove useful as an additional marker for screening for diabetic nephropathy and may help in the understanding of the contribution of renal tubular abnormalities to the nephropathic process.

Urinary growth hormone excretion as measured by a sensitive immunochemiluminometric assay.

A sensitive immunochemiluminometric assay with a detection limit of 1.1 microU/L was developed for the measurement of urinary growth hormone (UGH). The assay was shown to be specific and precise. There was a good correlation between serum growth hormone (GH) and UGH concentrations in 20 patients with acromegaly and six volunteers following an intravenous injection of recombinant GH. We concluded therefore that UGH measurements appear to provide a satisfactory index of GH secretion. The use of the assay in the investigation of growth disorders was assessed. We studied 11 pre-pubertal children, six of normal stature, and five of short stature, over a 6-month period. Sequential fortnightly measurements of UGH were carried out and height velocity was determined. The children of short stature grew at a slower rate and excreted less GH than the children of normal stature. However, we observed considerable within-individual variability in GH excretion in both groups (CV 22-98%). We therefore recommend that sequential UGH analyses should be carried out and the results interpreted in conjunction with growth measurements. However, further investigations into the renal handling of GH are needed to establish optimum sampling regimes.

Hyperparathyroidism, platelet intracellular free calcium and hypertension in chronic renal failure.

To investigate possible relationships between hyperparathyroidism, alterations in intracellular free calcium concentration ([Ca2+]i) and hypertension in chronic renal failure, serum concentrations of intact parathyroid hormone (PTH) were measured by two-site immunometric assay, and platelet ([Ca2+]i) was assessed using the fluorescent indicator fura-2. Thirty-six patients with chronic renal failure were studied, 10 with normal serum PTH concentrations (mean 8.0 +/- 0.6 pmol/liter), 17 with elevated serum PTH (35.0 +/- 7.2 pmol/liter) and 9 patients with elevated PTH (36.2 +/- 5.9 pmol/liter) who were receiving nifedipine. Platelet [Ca2+]i was increased in patients with elevated PTH, compared with those in whom PTH was normal (138 +/- 16 vs. 83 +/- 7 nmol/liter, P < 0.01). A linear relation was observed between serum PTH and platelet [Ca2+]i in these patients (r = 0.818, P < 0.001). In contrast, platelet [Ca2+]i was not elevated (84 +/- 9 nmol/liter) in the patients with elevated PTH who were receiving nifedipine. A linear relation was also present between both serum PTH (r = 0.616, P < 0.001) and platelet [Ca2+]i (r = 0.576, P < 0.005) and mean blood pressure. Nine patients with hyperparathyroidism were restudied after treatment with the vitamin D analogue alfacalcidol. This resulted in significant decreases in serum PTH (P < 0.01), platelet [Ca2+]i (P < 0.02), and mean blood pressure (P < 0.05). These studies indicate that [Ca2+]i may be increased early in renal failure, and that this increase occurs in association with both hyperparathyroidism and hypertension. Furthermore, treatment of hyperparathyroidism with alfacalcidol may result in reductions in both [Ca2+]i and blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunochemiluminometric assays (ICMA) specific for growth hormone releasing hormone 1-44 NH2 and 1-40 OH.

We describe specific two-site immunochemiluminometric assays able to directly measure human growth hormone-releasing hormone 1-44 NH2 and 1-40 OH concentrations in unextracted plasma. A common N-terminal antibody was purified from polyclonal rabbit antisera to growth hormone-releasing hormone 1-44 NH2 on a growth hormone-releasing hormone 1-29 NH2 linked affinity column and labelled with chemiluminescent acridinium ester. C-terminal specific monoclonal antibodies to growth hormone-releasing hormone 1-44 NH2 and 1-40 OH were raised in Balb/C mice and used as solid phase antibodies. Assay of fasting specimens from normal individuals gave medians (and ranges) of 23 pg/ml (2-200) and 30 pg/ml (3-134) for growth hormone-releasing hormone 1-44 NH2 and 1-40 OH, respectively. Samples from a series of acromegalics showed that most have values in the normal range though median values were higher, 56 pg/ml for growth hormone-releasing hormone 1-44 NH2 (P < 0.001) and 52 pg/ml for 1-40 OH (P < 0.001). Using these assays it will be possible for the first time to directly study the physiology and pathophysiology of these two peptides.

The relationship between adenoma weight and intact (1-84) parathyroid hormone level in primary hyperparathyroidism.

The relationship between preoperative serum levels of intact parathyroid hormone (PTH), serum calcium, and the weight of parathyroid adenoma has been investigated in 44 patients undergoing surgery for primary hyperparathyroidism due to single gland disease. There was no significant correlation between preoperative serum calcium and either intact PTH concentration or adenoma weight (r = 0.465 and 0.381, respectively). Although there was a significant correlation between PTH concentration and adenoma weight (r = 0.850, p less than 0.0005), this correlation was lost when two unusually heavy adenomas weighing 10.98 and 15.23 g were removed from the analysis. Clearly, a preoperative direct prediction of gland weight determined from PTH level was not possible. Patients with adenomata heavier than 750 mg had a significantly lower circulating PTH level per mg of adenoma than patients with glands lighter than 750 mg. PTH secretion in vitro in low calcium medium by adenoma cells from glands weighing less than 1 g was higher than secretion by cells from adenomas heavier than 1 g. Larger parathyroid adenomata appear to secrete less PTH per unit weight in vivo and per unit cell in vitro under conditions of maximal stimulation.

Preparation of a chemiluminescent imidoester for the non-radioactive labelling of proteins.

A chemiluminescent aryl acridinium ester was synthesized which possesses an imidate ester group capable of reacting with proteins under mild conditions. The compound can be detected at levels as low as 5.2 x 10(-19) mol using commercially available luminometers and can therefore be used to produce high specific activity labelled antibodies for use in immunochemiluminometric assays. The imidate ester compares favourably with a previously reported N-succinimidyl ester in terms of its labelling properties but is easier to synthesize, requiring one less step. The compound was used to label affinity purified to synthesize, requiring one less step. The compound was used to label affinity purified sheep antibodies to human parathyroid hormone to demonstrate its utility in a two-site immunochemiluminometric assay for the measurement of intact parathyroid hormone.

Calcium and phosphate metabolism in acute falciparum malaria.

1. Mineral homeostasis was investigated in 172 Thai adults with acute falciparum malaria at presentation (87 males, 85 females; mean age 30 years), and prospectively in a subgroup of 10 severely ill patients. 2. Mild, asymptomatic hypocalcaemia (corrected plasma calcium concentration 1.79-2.11 mmol/l) was found in 61 cross-sectional study patients (35.5%), with no difference between those with uncomplicated (2.16 +/- 0.10 mmol/l, mean +/- SD, n = 89) and severe (2.18 +/- 0.15 mmol/l, n = 83, P = 0.36) infections. Six prospectively studied patients were hypocalcaemic during treatment; simultaneous serum intact parathormone concentrations were inappropriately low (less than 5.0 pmol/l), but rose in three patients to high levels (11.8-16.4 pmol/l) on the fifth day. 3. Plasma phosphate concentration was decreased (less than 0.80 mmol/l) on admission in 74 patients (43.0%) and increased (greater than 1.45 mmol/l) in 15 (8.7%). Severe phosphate depletion (plasma phosphate concentration less than 0.30 mmol/l) occurred in 14 patients, of whom 11 had severe infections. Serum phosphate concentrations in the prospective study patients on admission (0.59 +/- 0.23 mmol/l) correlated significantly with the simultaneous renal threshold phosphate concentration (0.68 +/- 0.33 mmol/l; r = 0.607, P less than 0.025) and both parameters rose in parallel during treatment. 4. Plasma magnesium concentrations were normal (0.75-1.05 mmol/l) in 108 patients (62.8%); 45 cases (26.1%) had hypermagnesaemia and 19 (11.0%) had hypomagnesaemia. 5. These data suggest that mild hypocalcaemia is common in malaria regardless of disease severity; a depressed parathormone response may contribute. Despite malaria-associated haemolysis, hypophosphataemia is also common, but can be severe.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal insufficiency and secondary hyperparathyroidism in elderly patients.

Glomerular filtration rate (GFR) is frequently reduced in elderly people. However, the effect of this on mineral metabolism in this population has received little attention. GFR, serum intact parathyroid hormone (PTH) and vitamin D metabolites were measured in 37 patients admitted to hospital for various reasons. In 20 patients with GFR greater than 50 mL/min, an elevated serum intact PTH concentration (greater than 5.4 pmol/L) was found in two, while in 17 patients with GFR less than 50 mL/min PTH was elevated in 13. One of this group was hypercalcaemic and presumed to have primary hyperparathyrodism. Adjusted calcium was normal in all other patients. Two patients had a low serum 25-hydroxyvitamin D concentration (less than 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 less than 50 mL/min. We conclude that hyperparathyrodism 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.