长期卧床老年人的骨代谢和维生素d2、d3水平的状况研究

目的 观察长期卧床老年人的骨代谢变化及体内维生素D2和D3水平。方法 随机选取126位长期卧床（1年以上）的住院患者作为研究组,36位同年龄段的健康人作为对照组,采用高效液相色谱-质谱联用法（LC-MS/MS)定量测定两组人群的维生素D2和D3,并测定骨代谢指标和生化指标,分析两组之间的差别。结果 研究组与对照组的的血清钙、磷浓度、PTH、CT相比无差异（P>0. 05);骨形成指标AKP、N-MID相比无差异（P>0.05);骨吸收指标β-CTX相比有明显区别（P <0.01.。两组的25羟基维生素D2浓度无显著差异,研究组的25羟基维生素D3 10. 48 ±6. 54 ng/ml明显低于对照组25羟基维生素D3 15. 40 ±8. 19 ng/ml(P<0.01),总25羟基维生素D浓度研究组11.33 ±6.90 ng/ml也低于对照组15.33 ±8. 32 ng/ ml(P<0. 05)。总25羟基维生素D仅与PTH显著负相关,r= -0.362(P<0.01)。结论 卧床超过1年的老年人仍然存在骨吸收增高,骨丢失加快,同时维生素D缺乏明显,并加重了骨量流失。     

血清25（OH）D3与胰岛素抵抗及尿微量白蛋白的相关性研究

目的：观察2型糖尿病及糖调节受损患者血清25（OH）D3与胰岛素抵抗及尿微量白蛋白的相关性。方法：对820例健康体检人员进行筛查,共筛选出104例2型糖尿病患者（T2DM组）,其中初发糖尿病患者40例,既往诊断2型糖尿病患者64例,同时筛选出糖调节受损患者（IGR组）94例,选择同期170例非糖尿病血糖正常体检者为对照组（NGT组）。所有参与者记录身高、体重计算体重指数（ BMI）、并行口服糖耐量及胰岛素释放试验检测;留取血清,运用ELISA法检测血清25（OH）D3水平;放免法检测尿微量白蛋白（尿MA）;分析血清25（OH）D3与胰岛素抵抗及尿MA的相关性。结果：T2DM组及IGR组中25（OH）D3水平与对照组相比明显降低（P＜0.05）,2型糖尿病中有63.16%的患者维生素D缺乏,较非糖尿病患者（42.35%）明显增高（P＜0.05）;相关分析显示,血清25（OH）D3水平与空腹胰岛素呈正相关,而与年龄、BMI、空腹血糖水平、HOMA-IR、尿微量白蛋白呈负相关。结论：2型糖尿病患者血清维生素D缺乏非常严重,维生素D缺乏可能会加重胰岛素抵抗及促进尿微量白蛋白分泌。维生素D缺乏可能是2型糖尿病及糖尿病肾病发病中重要的危险因素。     

山西地区2012年至2013年我院就诊人群血清维生素D水平状况调查

目的 探讨目前山西地区不同季节人群的维生素D状况。方法 通过对2012 年6 月至2013年7月山西医科大学第二医院就诊的1313例患者血清25 羟维生素D [ 25（OH）D] 和甲状旁腺激素（PTH）水平,应用电化学发光免疫法测定血清25-羟维生素D[25（OH）D]、甲状旁腺激素（PTH）,按不同季节、性别进行分析。结果 ①所有检测人员的血清25(OH)D平均水平: 男性（11.38±6.29）ng/mL,女性（9.04±5.71）ng/mL。按照IOF维生素D水平判定标准:严重缺乏者占62.2%;维生素D缺乏者占28.46%;维生素D不足者占6.1%;维生素D充足者占3.25%。②血清25(OH)D水平与季节有显著相关性（r=0.228,P<0.05）;③血清25(OH)D与PTH 呈负相关（r=-0.272,P<0.05）。结论 受各种因素影响,目前山西地区成年人群中存在严重的维生素D不足和缺乏状况,应受到广泛的关注并改善现状,降低维生素D相关疾病的发病率。     

广州地区人群中血清25（OH）VitD的水平

目的评价广州正常人血清25（OH）VitD水平,探讨影响血清25（OH）VitD分布的因素。方法自2010年12月至2011年3月在我院体检人群中检查250名正常人（男性组150例,女性组100例,23～79岁）的血清25（OH）VitD水平。结果 250名正常人血清25（OH）VitD水平为17.80±5.35ng/mL,其中男性：18.54±5.37ng/mL;女性：16.71±5.15ng/mL。男性和女性人群血清25（OH）VitD水平差异无统计学意义（P〉0.05）。男性中VitD缺乏的占67.3%,女性中VitD缺乏的占79.0%。年龄与血清25（OH）VitD水平无线性相关性。结论 72.0%的广州正常成年人25（OH）VitD处于缺乏状态。     

529例成年女性维生素D水平及其影响因素研究

目的 回顾性分析529例成年女性血清25-羟维生素D［25 hydroxy vitamin D,25 ( OH) D］的水平及其影响因素,为骨质疏松症（osteoporosis,OP）及肥胖等疾病的防治提供依据。方法 选取2019年1月-2020年12月在黑龙江中医药大学附属第一医院接受血清25 (OH) D水平检测的成年女性,共计529人,其中19~28岁135人,29~38岁277人,39~48岁54人,49~58岁42人,59~68岁21人。采集受试者清晨空腹静脉血,应用酶联免疫法测定血清25 (OH) D浓度。以血清 25( OH)D＜30 nmol /L 为维生素 D缺乏;血清 25 (OH) D在30～49.9 nmol /L为维生素D不足;血清 25 (OH) D≥50 nmol /L为维生素D充足。统计数据并登记受试者性别、年龄以及采集时间等基本信息,分析血清25 (OH) D水平的影响因素。结果 529例成年女性25 (OH) D平均水平为（19.98±8.58）ng /mL,其中19~28岁组为（18.14±8.02）ng /mL,29~38岁组为（20.44±8.26）ng /mL,39~48岁组为（20.04±10.14）ng /mL,49~58岁组为（20.94±8.55）ng /mL,59-68岁组为（23.64±10.34）ng /mL。19~28岁人群维生素D水平充足的占比最低。不同年龄组相比较（完全随机方差分析one way ANOVA检验）,差异有统计学意义（F=2.88,P＜0.05）。经非参数检验,不同季节间差异有统计学意义（α=0.05）,夏季＞秋季＞春季＞冬季。结论 哈尔滨市成年女性普遍存在维生素D不足,且与年龄及季节具有相关性。     

不同阶段慢性肾脏病患者的25（OH）D3水平及相关性分析

目的为了解本地区不同阶段慢性肾脏病（chronic kidney disease,CKD）患者血清中25（OH）D3的水平,并探讨其水平与其他检测指标的关系。方法选择2013年1月至3月在我院肾病科住院的CKD非透析患者119例及同时期在我院体检的健康对照者30名（健康对照组）,采用酶联免疫法检测所有入选者25（0H）D3的水平,比较2组间25（0H）D3含量的差异,并分析其与体内其他生化指标的相关性。结果与健康对照组相比,CKD3～5期患者血清25（0H）D3含量均显著降低（PG0．05）,CKD患者血清25（OH）D3缺乏率达37．8％,不足率高达60．5％;CKD3～5期患者的血清甲状旁腺激素（PTH）、血肌酐（SCr）水平均显著升高（PG0．05）,CKD5期患者的血磷水平显著升高（P〈0．05）;25（OH）I）3与SCr、PTH、年龄、血糖（GLU）呈负相关（r=-0．480、-0．217、-0．604、-0．183,均PG0．05）;25（0H）D3与估算肾小球滤过率（eGFR）、血红蛋白（Hb）、血白蛋白（Alb）、性别、原发病种类呈正相关（r=0．569、0．512、0．359、0．200、0．300,均PG0．05）。结论本地区CKD3～5期患者的25（0H）D3水平明显下降,且CKD患者的25（OH）D3水平与SCr、eGFR、Alb、Hb、PTH等均存在一定的相关性。     

上海市绝经后妇女冬季维生素D状况

目的调查上海市绝经后妇女在冬季(12月份)维生素D的状况。方法在社区101例年龄63.7±7.0岁健康绝经后妇女中,检测血清25羟维生素D[25(OH)D]、甲状旁腺激素(PTH),同时检测血钙、磷、碱性磷酸酶、肝肾功能及空腹血糖。所有研究对象均用双能X线吸收仪检测腰椎和股骨近端骨密度(BMD),同时用问卷调查生活方式。结果本研究101例绝经后女性血清25(OH)D平均值为17.09 ng/ml,PTH平均值51.0 pg/ml,维生素D缺乏者占(<20 ng/ml)68%,维生素D不足者(20～29 ng/ml)占了30%,只有2例维生素D充足(>30 ng/ml)占2%。PTH均值在维生素D缺乏组中(53.7 pg/ml)高于维生素D不足组(44.8 pg/ml),有统计学差异(P<0.05);但未发现血清25(OH)D与PTH有线性回归关系。同时未发现血清25(OH)D与血钙、BMD或BMI相关。结论上海市健康绝经后妇女在冬季维生素D普遍不足,维生素D缺乏组的PTH显著高于维生素D不足组,不良的生活方式及低维生素D和钙的摄入应引起重视。     

活性维生素D3对体外原代培养人骨关节炎软骨细胞的影响

目的探讨不同浓度的1α,25二羟基维生素D3[1,25-（OH）2D3]对体外培养的人骨关节炎患者关节软骨细胞的增殖及凋亡率的影响。方法酶二步消化法体外分离培养人软骨细胞,以碱性磷酸酶染色法鉴定。加入不同剂量的[1,25-（OH）2D3],通过噻唑蓝比色试验检测细胞存活和增殖情况,以及用流式细胞仪检测软骨细胞在不同药物浓度、不同作用时间的凋亡率。结论 [1,25-（OH）2D3]作用于人骨关节炎软骨细胞的最佳作用浓度为1×10-5umol/L,最佳作用时间点为48 h。高浓度的[1,25-（OH）2D3]能明显促进细胞坏死,极低浓度的[1,25-（OH）2D3]对软骨细胞增殖、凋亡无明显影响。     

贵阳城区男性血清25( OH) D水平与血清PTH及骨密度的相关性研究

目的了解贵阳城区男性血清25(OH)D水平与血清PTH、骨密度之间关系的阈值。方法用整群抽样的方法横断面调查贵阳城区20~79岁(46.2±14.9岁)健康男性居民634名。研究对象均问卷调查健康状况,测定血钙、血磷、血肌酐、血清25(OH)D水平和血清PTH浓度(美国DiaSorin放射免疫试剂盒),测定非优势(左)股骨近端股骨颈(neck)、全髋部(hip)及腰椎前后位(L1-L4)的骨密度(BMD)值(美国GE公司Lunar Prodigy双能x线骨密度仪)。结果1.资料较齐全的571名受试者中,维生素D营养状况正常[25(OH)D≥30.0 ng/ml]仅为103名(18.0%),维生素D营养状况异常者[25(OH)D30.0ng/ml]高达82%;2.血清25(OH)D水平与血清PTH浓度呈负相关,当25(OH)D水平低于20 ng/ml时,PTH开始升高;3.青中年男性骨密度值随血清25(OH)D水平在20 ng/ml以上明显升高,老年男性血清25(OH)D水平在10 ng/ml各部位骨密度增高,但达到20 ng/ml后,骨密度增长缓慢。结论贵阳市城区男性低血清25(OH)D水平较常见,血清25(OH)D水平低于20 ng/ml可能会导致甲状旁腺激素水平升高,维生素D营养状况对不同年龄段男性骨密度部位影响可能不同。     

上海地区中老年人维生素D与骨密度之间的相关性调查

目的研究维生素D与骨密度的相关性。方法调查248名自由居住在上海的中老年人,女性128名,男性120名,年龄在40到90之间,他们都是从人口基数中随机选入的。分别测量选入对象的全身骨密度和血清中25(OH)D的含量,分析两者之间的相关性。结果研究对象的平均年龄70.03±11.44岁,其中男性的平均年龄为70.96±12.22岁,女性的平均年龄为69.16±10.62岁。研究对象的平均25(OH)D的总量浓度为13.733±6.894 ng/ml;平均25(OH)D2的浓度为1.672±1.577 ng/ml,平均25(OH)D3的浓度为12.057±6.631 ng/ml。其中男性平均25(OH)D的总量浓度为14.258±5.557 ng/ml;平均25(OH)D2的浓度为1.580±1.548 ng/ml,平均25(OH)D3的浓度为12.710±5.440 ng/ml。女性平均25(OH)D的总量浓度为13.241±7.937 ng/ml;平均25(OH)D2的浓度为1.758±1.604 ng/ml,平均25(OH)D3的浓度为11.445±7.550 ng/ml。研究对象中97%(n=241)25(OH)D的浓度小于30 ng/ml;其中男性中99%的人(n=119)25(OH)D的浓度小于30 ng/ml;女性中95%的人(n=122)25(OH)D的浓度小于30 ng/ml。研究对象中83%(n=206)的人伴有股骨颈骨质疏松;86%的人(n=214)伴有腰椎的骨质疏松。其中男性中82%的人(n=98)伴有股骨颈骨质疏松,84.2%的人(n=101)伴有腰椎的骨质疏松。女性中84.4%的人(n=108)伴有股骨颈骨质疏松,88.3%的人(n=113)伴有腰椎的骨质疏松。在多变量的数据分析里,校正了年龄、体重指数的差异后,发现25(OH)D与骨密度之间存在一定关系(见表3、4、5)。结论在中国上海健康中老年人群中存在严重的维生素D不足和缺乏状况,维生素D的状态与骨密度可能存在正性相关,必须进一步进行大样本的研究来探讨维生素D与骨质疏松症及骨折的关系。     

系统性红斑狼疮女性患者血清25(OH)D3水平测定及其与骨密度关系的研究

目的横断面观察系统性红斑狼疮(SLE)女性患者血清25(OH)D3的水平,统计其不足和缺乏的发生率;分析SLE患者血清25(OH)D3水平不足和缺乏的相关影响因素;研究血清中维生素D水平与疾病活动度(SLEDAI)、骨密度(BMD)等之间的相关性。方法选取无锡市第二人民医院2009年09月～2011年03月风湿科门诊及住院SLE未孕女性患者106例作为病例组,搜集患者资料;选取73例健康体检者作为对照组,采用酶联免疫法测定外周血血清中25(OH)D3的浓度,采用双能X线测量SLE组人员的BMD,进行各因素间相关分析。结果 106例SLE患者血清25(OH)D3水平较73例健康对照组显著低下(t=-10.422,P<0.001),影响因素有使用糖皮质激素、糖皮质激素使用剂量、肾脏受累。血清25(OH)D3水平与疾病活动度评分间有负相关(r=-0.602,P=0.023)。未接受糖皮质激素治疗的SLE患者血清25(OH)D3水平与BMD间有统计学相关性(r=0.178,P=0.012),而接受糖皮质激素患者两者之间无统计学相关性。结论女性SLE患者血清25(OH)D3水平较健康对照组显著低下,使用糖皮质激素、激素剂量、肾脏受累是其显著的影响因素;血清25(OH)D3水平与疾病活动度相关;未接受糖皮质激素治疗SLE患者血清25(OH)D3水平与BMD间有相关性。血清25(OH)D3的测定可为预测疾病活动程度、早期干预提供依据。     

Vitamin D Deficiency: A Common Occurrence in Both High-and Low-energy Fractures

As a consequence of newly elevated standards for normal vitamin D levels, there is a renewed interest in vitamin D insufficiency and deficiency (<32 and <20 ng/ml, respectively) in the orthopedic patient population. This study tests the hypothesis that vitamin D insufficiency is comparably prevalent among both high- and low-energy fracture patients. A retrospective analysis of the medical records for 44 orthopedic trauma in-patients with non-vertebral fractures was conducted from June 1, 2006 to February 1, 2007. The obtained data included a 25-hydroxyvitamin D level, age, gender, and reason for admission; high-energy vs. low-energy fracture. Vitamin D insufficiency, 25(OH)D <32 ng/ml, was found in 59.1% of the patients. Significantly, more women (75%) than men (40%) were vitamin D insufficient among all fracture patients and specifically among high-energy fractures, 80% women insufficient vs. 25% men insufficient. In women, both high- and low-energy fractures present with vitamin D insufficiency (80% of high-energy fractures and 71.4% of low-energy fractures). In men, the mean vitamin D level was lower for low-energy fractures (16 ng/ml) compared to high-energy fractures (32 ng/ml). In addition, men with low-energy fractures were significantly older than men with high-energy fractures and women with low-energy fractures were also older. Statistically, more vitamin D insufficiency is seen in women and our results are consistent with the gender difference seen in the general population. Even among younger men who sustain a high-energy fracture, 25% are vitamin D insufficient. Women with fractures regardless of age or fracture energy level have low vitamin D levels. Levels of 25(OH)D should be measured in all orthopedic trauma patients and the American Society for Bone and Mineral Research and National Osteoporosis Foundation currently recommend that vitamin D levels should be corrected.     

25-OH-D2、25-OH-D3与股骨颈骨密度的相关性研究

目的研究人体内25羟维生素D2(25-OH-D2)、25羟维生素D3(25-OH-D3)含量与股骨颈骨密度的相关性。方法利用双能X线骨密度测量法检测205例患者股骨颈骨密度,同时用高效液相色谱法检测其血清中25-OH-D2及25-OH-D3的含量,并根据维生素D(VitD)含量分析VitD与骨密度的关系。结果人体内VitD(25-OH-D2+25-OH-D3)含量与50岁以下者的股骨颈骨矿含量无相关性(P0.05),与50岁以上者呈正向直线相关(P0.05或P0.01),男女性别均一致。结论对于50岁以上者,随着年龄的增长,其体内血清VitD的含量降低很可能会导致其股骨颈骨矿含量下降。     

Calcidiol and PTH Levels in Women Attending an Osteoporosis Program

We performed a retrospective study of 237 patients attending a specialty osteoporosis practice. Secondary causes for reduced bone mineral density (BMD) were evaluated in 196 postmenopausal women and 41 premenopausal women; mean age was 56 ± 13.8 years (mean ± SD). BMD was measured by dual-energy X-ray absorptiometry (DXA) (QDR 1000W/2000 Hologic). Levels of intact parathyroid hormone (iPTH), calcidiol [25(OH)D], thyroid-stimulating hormone, and 24-hour urinary calcium were measured, and serum and urine protein (SPEP and UPEP) electrophoresis were performed. Overall, 16% of our patients had 25(OH)D levels <15 ng/ml, the lowest acceptable vitamin D level without a concomitant rise in iPTH levels. Among the osteoporotic patients (T score <−2.5 SD), 17% had 25(OH)D levels <15 ng/ml and 7% <10 ng/ml. Among the osteopenic patients (−2.5 < T < −1.0 SD), 11% had 25(OH)D levels <15 ng/ml. Seventeen percent of patients with Z score ≤−1.0 SD (low range normal value) had 25(OH)D levels <15 ng/ml. Low 25(OH)D levels were inversely related to high iPTH values (r = 0.30, P < 0.0001). Hypercalciuria was present in 15% of our patients, elevations of PTH levels (>65 pg/ml, upper normal limit of assay) were present in 11.5%, and hyperthyroidism in 4%. A 25(OH)D level of <25 ng/ml in women (n = 86) with no known secondary causes of low BMD was associated with an iPTH level above 49 pg/ml. The measurement of 25(OH)D levels is recommended in the evaluation of secondary causes for reduced BMD. Supplementation with vitamin D appears needed to keep 25(OH)D above 25 ng/ml, the level required to prevent increments in iPTH levels. Received: 9 February 1998 / Accepted: 1 October 1998     

Rapid correction of low vitamin D status in nursing home residents

Summary  This prospective study finds that ergocalciferol 50,000 IU three times weekly for four weeks effectively and safely corrects vitamin D inadequacy in nursing home residents. Introduction  Low vitamin D status is common among nursing home residents and contributes to bone loss, falls and fractures. The objective of this study was to evaluate the efficacy and safety of short course, high dose, oral vitamin D₂ (ergocalciferol) treatment. Methods  This prospective study included 63 nursing home residents. The 25 with low vitamin D status (serum 25(OH)D ≤ 25 ng/ml) received oral ergocalciferol 50,000 IU three times weekly for four weeks; the others received no change to their routine care. Serum total 25(OH)D, 25(OH)D₂, 25(OH)D₃, calcium, parathyroid hormone (PTH), bone turnover markers and neuro-cognitive assessments were obtained at baseline and four weeks. Results  Mean total 25(OH)D concentration increased (p < 0.0001) from 17.3 to 63.8 ng/ml in the treated group and remained unchanged in the comparison group. Serum 25(OH)D₃ remained stable in the comparison group, but declined (p < 0.0001) with D₂ treatment from 15.4 to 9.1 ng/ml. Serum PTH trended down in the treatment group (p = 0.06). No treatment-induced improvement in ambulation, cognition or behavior was observed. No hypercalcemia or other adverse effects were observed with ergocalciferol treatment. Conclusion  Four weeks of oral vitamin D₂ supplementation effectively and safely normalizes serum 25(OH)D in nursing home residents.     

Vitamin D status and its relationship with bone mineral density in healthy Asian Indians

Synthesis of vitamin D takes place in the skin under the effect of sunlight. The Indian subcontinent is situated between 8.4° N and 37.6° N latitudes and has adequate sunshine throughout the year. Thus, it has been presumed that Indians are vitamin D sufficient. We measured serum 25-hydroxy vitamin D [25(OH)D] (n=92) and 1,25-dihydroxy vitamin D [1, 25(OH)₂D] (n=65) levels in healthy hospital staff, using ¹²⁵I radioimmunoassay. Serum intact parathyroid hormone (PTH) concentration was estimated by immunoradiometric assay. Bone mineral density was estimated using a dual energy X-ray absorptiometer (Hologic^R QDR 4500A). Using a serum 25(OH)D level of 15 ng/ml as a cutoff, 66.3% (61/92) of the subjects were found to be vitamin D deficient. Of these, 20.6% (19/92) subjects had severe vitamin D deficiency (<5 ng/ml), 27.2% (25/92) had moderate vitamin D deficiency (5–9.9 ng/ml), while 18.5% (17/92) had mild vitamin D deficiency (10–14.9 ng/ml). When a serum 25(OH)D level of 20 ng/ml was used as a cutoff, 78.3% subjects were diagnosed to be vitamin D deficient/insufficient. The serum 1,25(OH)₂D level was within the normal range (40.6±20.1 pg/ml; mean ± SD). Mean (±SD) serum intact PTH, estimated in a limited number of subjects (n=15), was 72.3 (±21.0) pg/ml (range 36–100 pg/ml). There was a significant correlation between daily sun exposure and 25(OH)D levels (r=0.731, P<0.001). The serum 25(OH)D level correlated with BMD at the femoral neck and Ward's triangle (r=0.50, P=0.020 and r=0.46, P=0.037, respectively). Our findings show that vitamin D deficiency is common in urban north Indian hospital staff. The possible reasons include inadequate sunlight exposure and skin pigmentation in Indians. The serum 1,25(OH)₂D level is not a good indicator of vitamin D deficiency. A low serum 25(OH)D level is possibly one of the reasons for lower bone mineral density among Indians.     

Vitamin D Does Not Increase Calcium Absorption in Young Women: A Randomized Clinical Trial

It is commonly said that vitamin D should be used to increase calcium absorption. We tested this statement in a dose‐response study of vitamin D on calcium absorption. A total of 198 white and African American women, aged 25 to 45 years, with vitamin D insufficiency, serum 25‐hydroxyvitamin D (25OHD) <20 ng/mL, were randomized in a double‐blind study to vitamin D3 400, 800, 1600, 2400 IU, or placebo. A calcium supplement was given to increase mean calcium intake at baseline from 706 mg/d to 1031 mg/d. Calcium absorption was measured at baseline and after 12 months using a single isotope method with radiocalcium45 and 100 mg of calcium. Mean baseline serum 25OHD was 13.4 ng/mL (33.5 nmol/L) and increased to 40 ng/mL (100 nmol/L) on the highest dose of 2400 IU. Using a multivariate regression analysis with significant predictors, baseline absorption, calcium intake, and weight, there was no increase in 12‐month calcium absorption compared with baseline on any dose of vitamin D in either whites or African Americans. There was no significant relationship between 12‐month calcium absorption and final serum 25OHD. In an analysis of calcium absorption and serum 25OHD at baseline, serum 25OHD levels were divided into groups: 0 to 5, 6 to 10, 11 to 15, or 16 to 20 ng/mL. There was no evidence of a threshold decrease in calcium absorption or serum 1,25 dihydroxyvitamin D (1,25(OH)₂D) amongst the lowest groups. Vitamin D doses up to 2400 IU daily did not increase calcium absorption. No threshold level of serum 25OHD for calcium absorption was found at baseline or in the longitudinal study, suggesting that active transport of calcium is saturated at very low serum 25OHD levels <5 ng/mL. There is no need to recommend vitamin D for increasing calcium absorption in normal subjects. Very efficient calcium absorption at very low levels of serum 25OHD explains why people do not develop osteomalacia provided that dietary intakes of calcium and phosphorus are adequate. © 2014 American Society for Bone and Mineral Research.     

Vitamin D insufficiency and hyperparathyroidism in children with chronic kidney disease

Chronic kidney disease (CKD) is associated with altered calcium-phosphate homeostasis and hyperparathyroidism due to decreased activity of 1alpha-hydroxylase and impaired activation of 25-hydroxyvitamin D3 [25(OH)D3]. In some patients these problems start earlier because of vitamin D deficiency. A retrospective review of patients followed in the chronic renal insufficiency clinic at Children's Hospital of Michigan assessed the prevalence of vitamin D deficiency in CKD stages 2-4 and evaluated the effect of treatment with ergocalciferol on serum parathormone (PTH). Blood levels of 1,25 dihydroxyvitamin D3, 25(OH)D3, and parathormone (PTH) were examined in 57 children (40 boys; mean age 10.6 years). Of 57 subjects, 44 (77.2%) had 25(OH)D3 levels 30 ng/ml was 67.84 +/- 29.09 ng/ml and in the remaining patients was elevated, at 120.36 +/- 86.42 ng/ml (p = 0.05). Following ergocalciferol treatment (22), PTH decreased from 122.13 +/- 82.94 ng/ml to 80.14 +/- 59.24 ng/ml (p < 0.001) over a period of 3 months. We conclude that vitamin D deficiency is common in children with CKD stages 2-4 and is associated with hyperparathyroidism in the presence of normal 1,25 dihydroxyvitamin D3. Its occurrence before significant renal impairment is noteworthy. Early diagnosis and appropriate treatment is emphasized.