Temporal Interrelationships Between the Circadian Rhythms of Serum Parathyroid Hormone and Calcium Concentrations*

Abstract

The temporal relationships between the circadian rhythms of serum PTH, total calcium (Cat), and phosphate (Pi) and plasma ionized calcium (Cai) concentrations were determined in 9 normal men. Blood samples were collected every half hour for 24 h. Serum PTH was measured by an RIA specific for the midregion of the molecule. The mean circadian pattern for each variable was derived by calculating the average value across all men at concurrent time points. After the data were smoothed by the method of running means, the correlations between PTH and mineral values from concurrent time points were calculated, as were cross-correlations to 12 lag periods (6 h). Spectral and cross-spectral analyses were performed on the same data set. Both statistical methods yielded consistent results: 1) at concurrent time points (0 lag), high correlations were found between serum PTH and Cat (r = -0.74), PTH and Pi (r = 0.79), and PTH and Cai (r = -0.53); and 2) when the PTH series was lagged by 2 h, the PTH/Cai correlation improved to -0.70. A direct PTH/Cai correlation of 0.50 was found when the Cai series was lagged about 4.5 h. No improvement in the correlations were found when the other series were lagged. Spectral analyses also detected significant interrelations between PTH and Cai at 2 and 3.5 h. These data describe the timing of the bidirectional interaction between serum PTH and plasma Cai under steady state conditions in normal adult men; changes in Cai concentrations precede inverse changes in PTH levels by 2 h, whereas changes in PTH precede similar directional alterations in Cai by about 4 h.

Diurnal rhythm of plasma 1,25-dihydroxyvitamin D and vitamin D-binding protein in postmenopausal women: relationship to plasma parathyroid hormone and calcium and phosphate metabolism

“…This temporal sequence does not support the concept that the circadian variations in We found a diurnal pattern of plasma total and albumin-adjusted calcium similar to that reported in previous studies with low levels during the night, a peak in the forenoon and high levels during the day (19,20,24). Our finding that plasma calcium and PTH levels correlated negatively is in agreement with most previous studies (24). Food intake is known to be a major determinant of renal calcium excretion, as a rapid rise in calcium excretion occurs after a meal (6,22).…”

“…However, in our study, total plasma 1,25(OH) 2 D as well as the free 1,25(OH) 2 D index showed a nadir in the morning with an increase in the day time during which regular meals were served. This temporal sequence does not support the concept that the circadian variations in We found a diurnal pattern of plasma total and albumin-adjusted calcium similar to that reported in previous studies with low levels during the night, a peak in the forenoon and high levels during the day (19,20,24). Our finding that plasma calcium and PTH levels correlated negatively is in agreement with most previous studies (24).…”

L-Amino acid sensing by the calcium-sensing receptor: a general mechanism for coupling protein and calcium metabolism?

“…The origin of the circadian rhythm for PTH, however, is not clear. It is not driven by changes in serum ionized Ca 2þ concentration which exhibits one or more troughs during the afternoon but is largely stable between midnight and 06:00 h (Calvo et al, 1991;Markowitz et al, 1988). Nevertheless, the diet exerts a considerable influence because the circadian rhythm for PTH is abolished by fasting over several days (Fraser et al, 1994).…”

Sampling and storage conditions influencing the measurement of parathyroid hormone in blood samples: a systematic review

“…Logue et al [81] recommend that blood samples should be collected between 10:00 and 16:00 and results interpreted against a reference range based on this [65] 12.00-20.00 -20.00 08.00 Calvo et al [67] 02.00-04.00 18.00-20.00 18.00 and 02.00 10.00 and 20.00 Chapotot et al [68] 23.00-07.00 15.00-23.00 --El-Hajj et al [69] 01.00-03.00 17.30 03.14 10.00-11.00 Fraser et al [71] 22.00-07.00 14.00-22.00 06.12 09.30-10.30 Generali et al [72] --17.15 -Greenspan et al [74] 03.20 15.20 -12.00 Greenspan et al [75] 23.35 ± 05.25 , 20.30 ± 02.10 ---Herfarth et al [76] No night samples P.M. 14.00 09.30 Joseph et al [77] 22.00-24.00 , 24.00-02.00 14.00-17.00 09.46-13.15 , 10.45-13.25 -Jubiz et al [78] 02.00-04.00 --08.00 Kitamura et al [79] A.M. -23.00 ± 4 -Logue et al [82] 02.00-06.00 -04.05 10.00 Logue et al [81] A.M. -04.05 09.30 Markowitz et al [83] 04.00 20.00 --Nielsen et al [84] P.M. sampling time. Since the data were derived using first or second generation assays, it is possible that the reported diurnal variation of PTH could reflect differential clearance of PTH fragments over a 24 h period, e.g., with reduced renal clearance of (7-84) PTH at night reflecting decreased glomerular filtration rate at night [92].…”