The modulation of circulating parathyroid hormone immunoheterogeneity in man by ionized calcium concentration

During the study of parathyroid function in 19 hemodialysis patients with low turnover aluminum bone disease, it was observed that serum parathyroid hormone (PTH) levels were higher during the induction of hypocalcemia than during the recovery from hypocalcemia. This type of PTH response has been termed hysteresis. Hypocalcemia was induced during hemodialysis with a calcium-free dialysate. When the total serum calcium level decreased to 7 mg/dL, the dialysate calcium concentration was changed to 3.5 mEq/L and the dialysis session was completed. One week later, hypercalcemia was induced during hemodialysis with a high-calcium dialysate. The mean basal PTH level was 132 +/- 37 pg/mL (normal, 10 to 65 pg/mL; immunoradiometric (IRMA), Nichols Institute, San Juan Capistrano, CA) and increased to a maximal PTH level of 387 +/- 91 pg/mL during hypocalcemia. For the same ionized calcium concentration, the PTH level was higher during the induction of hypocalcemia than during the recovery from hypocalcemia. Conversely, for the same ionized calcium concentration, the PTH level was greater when hypercalcemia was induced from the nadir of hypocalcemia than when hypercalcemia was induced from basal serum calcium. The set point of calcium (defined as the serum calcium concentration required to reduce maximal PTH by 50%) was greater during the induction of hypocalcemia than during the recovery from hypocalcemia (4.44 +/- 0.10 versus 4.25 +/- 0.09 mg/dL; P = 0.03). The mean basal ionized calcium concentration and the mean ionized calcium concentration at the intersection of the two PTH-calcium curves were the same (4.61 +/- 0.13 versus 4.61 +/- 0.12 mg/dL).(ABSTRACT TRUNCATED AT 250 WORDS)

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The modulation of circulating parathyroid hormone immunoheterogeneity in man by ionized calcium concentration.

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jcem.74.3.1740486 ◽

1992 ◽

Vol 74 (3) ◽

pp. 525-532 ◽

Cited By ~ 3

Author(s):

P D'Amour ◽

J Palardy ◽

G Bahsali ◽

L E Mallette ◽

A DeLéan ◽

...

Keyword(s):

Parathyroid Hormone ◽

Calcium Concentration ◽

Ionized Calcium

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Hypocalcemia and parathyroid hormone responsiveness in diabetes mellitus: a tri-sodium-citrate clamp study

Acta Endocrinologica ◽

10.1530/acta.0.1260260 ◽

1992 ◽

Vol 126 (3) ◽

pp. 260-263 ◽

Cited By ~ 24

Author(s):

Peter Schwarz ◽

Henrik A Sørensen ◽

Günther Momsen ◽

Thorkild Friis ◽

lb Transbøl ◽

...

Keyword(s):

Diabetes Mellitus ◽

Parathyroid Hormone ◽

Calcium Concentration ◽

Sodium Citrate ◽

Insulin Dependent Diabetes Mellitus ◽

Insulin Dependent Diabetes ◽

Ionized Calcium ◽

Dependent Diabetes Mellitus ◽

Insulin Dependent ◽

Clamp Study

The aim of this study was to elucidate the diabetic hypocalcemia and PTH responsiveness, investigated by measuring blood ionized calcium and serum intact parathyroid hormone (S-PTH(1–84)) concentrations, before and during an induced and maintained controlled hypocalcemia. In 15 patients with insulin-dependent diabetes mellitus and 19 healthy volunteers the blood ionized calcium concentration was lowered by about 0.20 mmol/l and maintained at this level by blood ionized calcium controlled tri-sodium-citrate infusion. In patients vs controls, baseline measurements averaged for blood ionized calcium (mmol/l) 1.18±0.08 vs 1.24±0.03 (p<0.01), for S-magnesium (mmol/l) 0.73±0.07 vs 0.81±0.07 (p<0.01) and for S-PTH (1–84) (pmol/l) 3.0±1.0 vs 3.1±1.0 (p>0.75). During the clamp. S-PTH (1–84) peaked to comparable maximums after 5–10 min in both groups and then declined to constant concentrations two to three times above their control levels. In conclusion, we found a diabetic hypocalcemia and hypomagnesemia, though baseline levels of PTH and PTH responsiveness were normal. This may be taken to indicate a mild shift downwards in the set-point for PTH secretion in patients with insulin-dependent diabetes mellitus.

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Calcium metabolism and cardiovascular function after spaceflight

Journal of Applied Physiology ◽

10.1152/jappl.2002.92.1.3 ◽

2002 ◽

Vol 92 (1) ◽

pp. 3-12 ◽

Cited By ~ 14

Author(s):

Daniel C. Hatton ◽

Qi Yue ◽

Jacqueline Dierickx ◽

Chantal Roullet ◽

Keiichi Otsuka ◽

...

Keyword(s):

Parathyroid Hormone ◽

Calcium Metabolism ◽

Calcium Concentration ◽

Dietary Calcium ◽

Ionized Calcium ◽

Free Calcium ◽

Mineral Density ◽

Spontaneously Hypertensive ◽

Low Calcium ◽

High Calcium

To determine the influence of dietary calcium on spaceflight-induced alterations in calcium metabolism and blood pressure (BP), 9-wk-old spontaneously hypertensive rats, fed either high- (2%) or low-calcium (0.02%) diets, were flown on an 18-day shuttle flight. On landing, flight animals had increased ionized calcium ( P < 0.001), elevated parathyroid hormone levels ( P < 0.001), reduced calcitonin levels ( P < 0.05), unchanged 1,25(OH)2D3levels, and elevated skull ( P < 0.01) and reduced femur bone mineral density. Basal and thrombin-stimulated platelet free calcium (intracellular calcium concentration) were also reduced ( P < 0.05). There was a tendency for indirect systolic BP to be reduced in conscious flight animals ( P = 0.057). However, mean arterial pressure was elevated ( P < 0.001) after anesthesia. Dietary calcium altered all aspects of calcium metabolism ( P < 0.001), as well as BP ( P < 0.001), but the only interaction with flight was a relatively greater increase in ionized calcium in flight animals fed low- compared with high-calcium diets ( P < 0.05). The results indicate that 1) flight-induced disruptions of calcium metabolism are relatively impervious to dietary calcium in the short term, 2) increased ionized calcium did not normalize low-calcium-induced elevations of BP, and 3) parathyroid hormone was paradoxically increased in the high-calcium-fed flight animals after landing.

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Stimulation of parathyroid hormone secretion by EDTA infusion – a test for the differential diagnosis of hypercalcaemia

Acta Endocrinologica ◽

10.1530/acta.0.1110498 ◽

1986 ◽

Vol 111 (4) ◽

pp. 498-506 ◽

Cited By ~ 34

Author(s):

Lars Benson ◽

Jonas Rastad ◽

Leif Wide ◽

Göran Åkerström ◽

Sverker Ljunghall

Keyword(s):

Parathyroid Hormone ◽

Healthy Subjects ◽

Calcium Concentration ◽

Reference Range ◽

Hormone Secretion ◽

Serum Levels ◽

Ionized Calcium ◽

Healthy Control ◽

Edta Infusion ◽

Stimulation Of

Abstract. A constant EDTA infusion of 24 mg/kg/h during 60–120 min was given to 26 patients with primary hyperparathyroidism (HPT), 8 patients with hypercalcaemia of other origin and 10 healthy control subjects. PTH and ionized calcium concentrations were measured at 5–10 min intervals. In all three groups the infusion caused a linear decrease in plasma ionized calcium. In both the HPT patients and the healthy subjects there was a prompt increase in the serum levels of parathyroid hormone (PTH) until a plateau was reached. The PTH response of the HPT patients appeared already within the hypercalcaemic range and the plateau value was attained at higher levels of PTH and ionized calcium than in the healthy subjects. The enhanced response distinguished half of the HPT patients with basal PTH values within the reference range from the healthy controls. The patients with nonhyperparathyroid hypercalcaemia displayed no increase in PTH values until the ionized calcium concentration was reduced far into or below the reference range. Thus the EDTA infusion permitted a complete differentiation between HPT and other causes of hypercalcaemia. In most cases an infusion over 30 min was sufficient for this purpose.

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Platelet cytosolic free calcium concentration and parathyroid hormone: changing relationships with haemodialysis in end-stage renal disease

Clinical Science ◽

10.1042/cs0820651 ◽

1992 ◽

Vol 82 (6) ◽

pp. 651-658 ◽

Cited By ~ 2

Author(s):

R. J. Fluck ◽

A. C. McMahon ◽

F. M. Alameddine ◽

A. B. S. Dawnay ◽

L. R. I. Baker ◽

...

Keyword(s):

Parathyroid Hormone ◽

Calcium Concentration ◽

Cytosolic Calcium ◽

Ionized Calcium ◽

Free Calcium ◽

Dialysis Session ◽

Hormone Concentration ◽

Serum Parathyroid Hormone ◽

Cytosolic Calcium Concentration ◽

End Stage

1. Twelve patients receiving haemodialysis for end-stage renal failure were studied at a single dialysis session. Platelet cytosolic calcium concentration, plasma ionized calcium concentration and serum parathyroid hormone concentration were measured before dialysis, mid-dialysis and 30 min after dialysis. 2. Plasma ionized calcium concentration increased towards dialysate calcium concentrations, falling insignificantly after cessation of dialysis. Serum parathyroid hormone concentration fell by 39% during dialysis, with incomplete recovery afterwards. There was no overall change in platelet cytosolic calcium concentration. 3. Patients were divided into two subgroups: low parathyroid hormone (serum parathyroid hormone concentration < 10 pmol/l) and high parathyroid hormone (serum parathyroid hormone concentration > 10 pmol/l). Before dialysis, values of platelet cytosolic calcium concentration or plasma ionized calcium concentration were not statistically different between the subgroups, but the platelet cytosolic calcium concentration was higher in the high-parathyroid hormone subgroup during and after dialysis. 4. Before haemodialysis there was a linear correlation between plasma ionized calcium concentration and platelet cytosolic calcium concentration, which disappeared during dialysis. In contrast, there was no relationship between serum parathyroid hormone concentration and platelet cytosolic calcium concentration before dialysis, but after dialysis a hyperbolic relationship was evident. 5. These results suggest that uraemic toxins may interfere with cytosolic calcium homoeostasis, allowing passive diffusion of extracellular calcium to influence the resting concentration, and that this effect is reversible by haemodialysis.

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