A mathematical model of parathyroid hormone response to acute changes in plasma ionized calcium concentration in humans

2010 ◽  
Vol 226 (1) ◽  
pp. 46-57 ◽  
Author(s):  
Rajiv P. Shrestha ◽  
Christopher V. Hollot ◽  
Stuart R. Chipkin ◽  
Claus P. Schmitt ◽  
Yossi Chait
Keyword(s):  
Mathematical Model ◽  
Parathyroid Hormone ◽  
Calcium Concentration ◽  
Ionized Calcium ◽  
Hormone Response ◽  
Acute Changes

A Mathematical Model of Parathyroid Hormone Response to Acute Changes in Plasma Ionized Calcium Concentration in Humans

2008 ◽  
Author(s):  
Rajiv P. Shrestha ◽  
Yossi Chait ◽  
Christopher V. Hollot ◽  
Stuart Chipkin ◽  
Claus P. Schmitt
Keyword(s):  
Calcium Concentration ◽  
Linear Time ◽  
Ionized Calcium ◽  
Time Varying ◽  
Qualitative Model ◽  
Hormone Response ◽  
Clinical Tests ◽  
Parametrization Scheme ◽  
Normal Humans ◽  
Acute Changes

A complex bio-mechanism, referred to as calcium homeostasis, regulates plasma ionized calcium (Ca++) concentration in the human body to within a narrow physiologic range which is crucial for maintaining normal physiology and metabolism. In this paper we present a qualitative model of the calcium homeostatic system and then focus on a particular sub-system, termed Ca-PTH axis. We consider the dynamics of the axis involving the response of the parathyroid glands to acute changes in plasma Ca++ concentration. We use a two-pool, linear time-varying model to describe the Ca-PTH axis. We show that this model, parameterized using a guided iterative parametrization scheme and induced hypocalcemic clamp test data, successfully predicts dynamics observed in clinical tests of induced hypercalcemia in normal humans.

scholarly journals Hysteresis of the parathyroid hormone response to hypocalcemia in hemodialysis patients with low turnover aluminum bone disease.

1991 ◽  
Vol 2 (6) ◽  
pp. 1136-1143
Author(s):  
A J Felsenfeld ◽  
D Ross ◽  
M Rodriguez
Keyword(s):  
Parathyroid Hormone ◽  
Serum Calcium ◽  
Bone Disease ◽  
Calcium Concentration ◽  
Hemodialysis Patients ◽  
Ionized Calcium ◽  
Total Serum ◽  
High Calcium ◽  
The Mean ◽  
Pth Level

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)

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

1992 ◽  
Vol 74 (3) ◽  
pp. 525-532 ◽  
Author(s):  
P D'Amour ◽  
J Palardy ◽  
G Bahsali ◽  
L E Mallette ◽  
A DeLéan ◽  
...  
Keyword(s):  
Parathyroid Hormone ◽  
Calcium Concentration ◽  
Ionized Calcium

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

1992 ◽  
Vol 126 (3) ◽  
pp. 260-263 ◽  
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.

scholarly journals Calcium metabolism and cardiovascular function after spaceflight

2002 ◽  
Vol 92 (1) ◽  
pp. 3-12 ◽  
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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