Parathyroid response to Vitamin D among obese

Usually, as vitamin D levels are increased the parathyroid levels are decreased
May not be the case for obese
Trying to figure out what this means
This relationship between increased Vitamin D and decreased PTH
is a good indication that increased Vitamin d is actually getting to the cells, not just to the blood

Items in both of the categories of Thyroid/Parathyroid AND Obesity
PTH decreased with 1,000 IU, but no more with 4,000 IU in obese blacks - 2020
Different threshold for obese adolescents - 2021
Perhaps bioavailable ia a better measure than total for Obese Children - 2021
PTH, Children, Obesity - 2019
39 PTH studies in VitaminDWiki

Items in both of the categories of Thyroid/Parathyroid AND Obesity__

PTH decreased with 1,000 IU, but no more with 4,000 IU in obese blacks - 2020

Obesity and efficacy of vitamin D 3 supplementation in healthy black adults
Hanseul Kim 1, Paulette Chandler 2, Kimmie Ng 3, JoAnn E Manson 1 2, Edward Giovannucci 4 5 6
PMID: 32052217 PMCID: PMC7087388 DOI: 10.1007/s10552-020-01275-3

Purpose: Results from recent clinical trials suggest that vitamin D efficacy against cancer may be influenced by body mass index. As suppression of parathyroid hormone (PTH) is one indicator of vitamin D efficacy, we examined to what extent doses of vitamin D3 supplementation suppress PTH levels in individuals with and without obesity.

Methods: A total of 328 healthy African Americans were randomized into the following four groups and treated for 3 months: placebo, 1,000, 2,000, or 4,000 IU/day of vitamin D3 supplementation.

Results: Among the participants, 250 individuals with PTH measurements were included in the analysis. Obese individuals (n = 141) experienced a steep reduction of 3-month PTH from placebo to 1,000 IU/day of vitamin D3 supplementation, but no further reduction at 2,000 or 4,000 IU/day. For non-obese individuals (n = 109), the reduction of 3-month PTH was approximately linear for increasing vitamin D3 doses. At supplementation of 2,000 to 4,000 IU/day, 3-month 25(OH)vitamin D levels were high in both non-obese and obese individuals, but the 3-month PTH levels remained about 10 pg/mL higher in individuals with obesity.

Conclusion: Our findings suggest that excess adiposity confers resistance to vitamin D efficacy in suppressing PTH levels, even when given at high doses.
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Different threshold for obese adolescents - 2021

Different threshold levels of circulating total and free 25-hydroxyvitamin D for the diagnosis of vitamin D deficiency in obese adolescents
Eur J Pediatr . 2021 Jun 11. doi: 10.1007/s00431-021-04137-5
The total serum 25-hydroxyvitamin D [25(OH)DT] level is lower in obese individuals than in their nonobese peers, despite similar bone turnover markers and bone mineral density. This study aimed to investigate whether the threshold level of 25(OH)D for the diagnosis of vitamin D deficiency (VDD) in obese adolescents was lower than that in controls and to compare 25(OH)DT, free [25(OH)DF] and bioavailable [25(OH)DB] vitamin D with VDBP levels in obese individuals and their controls. A total of 173 adolescents (90 obese individuals and 83 controls) aged 12-18 years were included in the study. The metabolic and anthropometric parameters of the participants were recorded, the 25(OH)DT, 25(OH)DF, and VDBP levels were measured, and the 25(OH)DB levels were calculated. The cutoff values for VDD were estimated according to the level of 25(OH)D below which parathyroid hormone begins to rise. The obese subjects had lower 25(OH)DT (12.1 ± 5.8 vs. 16.4 ± 9.3 ng/mL, p < 0.001), 25(OH)DF (12.6 ± 4.2 vs. 16.7 ± 7.6 pg/mL, p < 0.001), 25(OH)DB [4.8 (2.3) vs. 6.1 (5.2) ng/mL, p = 0.012], and VDBP [112.2 (51.3) vs. 121.9 (95.5) μg/mL, p < 0.001] levels than the controls. The cutoff values for 25(OH)DT and 25(OH)DF levels for VDD were lower in the obese group than in the control group (9.4 vs. 14.1 ng/mL; 12.2 vs. 16.8 pg/mL, respectively).

Conclusion: The vitamin D cutoff values for the diagnosis of VDD were different in the obese and control groups. Using the same cutoff value for VDD may cause overtreatment in obese adolescents.
What is Known:

Vitamin D deficiency is more prevalent in obese children than nonobese controls, despite the same bone turnover markers and bone mineral density
The cutoff value of vitamin D level for the diagnosis of VDD is based on the PTH elevation

What is New:

In obese adolescents, total and free vitamin D cutoff value for the diagnosis of VDD was lower than nonobese peers
Using the same cutoff value for vitamin D deficiency in both obese and nonobese adolescents may cause overtreatment.

Perhaps bioavailable ia a better measure than total for Obese Children - 2021

Is Bioavailable Vitamin D Better Than Total Vitamin D to Evaluate Vitamin D Status in Obese Children?
J Clin Res Pediatr Endocrinol . 2021 May 20. doi: 10.4274/jcrpe.galenos.2021.2020.0230.
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Introduction: Free hormones are biologically more active in the target tissues. So we wanted to evaluate the vitamin D adequacy with bioavailable and free vitamin D. In order to calculate the bioavailable and free vitamin D according to the previously reported formula, VDBP level was measured. VDBP polymorphisms were also evaluated as they can affect the binding affinity.

Methods: Eighty-four obese and 78 healthy children included in the study. Anthropometry, calcium, phosphorus, alkaline-phosphatase, parathyroid hormone, 25 (OH) vitamin D, bioavailable-free vitamin D, VDBP level and polymorphism were evaluated in the whole group.

Results: When the girls compared within themselves, PTH values were found to be higher in the obese group (p=0.001). When we compared obese and control subjects without gender discrimination, VDBP and PTH levels were found to be statistically higher in the obese group(respectively p=0.008, p=0.002). When only the cases included in the winter period were analyzed, PTH and VDBP were found to be higher and bioavailable and free vitamin D lower in the obese group. There was no difference in terms of total vitamin D between groups during the winter season.

Discussion/conclusion: While total, free, bioavailable vitamin D in obese group was similar to the control group in autumn, free and bioavailable vitamin D in the winter was lower than the control group. Also PTH was higher in obese group than the control group in both autumn and winter. Therefore, many more studies are needed to evaluate the variability of free, bioavailable vitamin D according to the seasons and its effects.

PTH, Children, Obesity - 2019

The relation between circulating levels of vitamin D and parathyroid hormone in children and adolescents with overweight or obesity: Quest for a threshold
The level of serum 25-hydroxyvitamin D (25(OH)D) at which intact parathyroid hormone (iPTH) is maximally suppressed (suppression point) and below which PTH begins to rise (inflection point) has been used to define optimum 25(OH)D concentration. We aimed to study the association of circulating iPTH with 25(OH)D concentrations and to determine a 25(OH)D threshold associated with a significant iPTH suppression. This cross-sectional study was conducted on 198 boys and 180 girls, aged 6–13 years with BMI ≥ 1SD (WHO criteria) recruited from primary schools. Adjusted iPTH for BMI z-score, pubertal status, and dietary calcium was used. Nonlinear regression was used to model the relationship between 25(OH)D and iPTH and identify a suppression point for 25(OH)D at which iPTH reached a plateau. Piecewise regression analysis with a single knot for all possible values of 25(OH)D were fitted. Furthermore, 95% confidence intervals (95%CI) for those point had been calculated. The mean age (SD) of girls and boys was 9.1 (1.6) and 9.4 (1.7) years, respectively. Median 25(OH)D and iPTH were 13.8 ng/mL and 33.9 pg/mL in boys and 9.9 ng/mL and 47.8 ng/mL in girls, respectively. The equation in girls was: log-iPTH = 3.598+0.868 exp[(-0.190×25(OH)D]. The point for near maximal suppression of iPTH by 25(OH)D for girls occurred at a 25(OH)D concentration of 20 ng/mL (95% CI: 7.1 to 32.2). No point of maximal suppression was found for boys. We also found a 25(OH)D threshold of 10 ng/mL (95% CI: 4.6 to 22.5) for girls (f: 9.8) by linear piecewise regression modeling of adjusted iPTH. No significant inflection point for boys was observed. In overweight/obese girls, when the concentration of 25(OH)D was higher than 20 ng/mL, an iPTH mean plateau level is reached, and when its concentrations approach 10 ng/mL, the slope of iPTH concentration has been accelerated.
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