X-linked hypophosphatemia: Normal renal function despite medullary nephrocalcinosis 25 years after transient vitamin D2-induced renal azotemia

Nephrocalcinosis (NC) detected by ultrasound is a recognized abnormality for some patients with X-linked hypophosphatemia (XLH) who received vitamin D₂ and inorganic phosphate therapy, but is commonly observed in XLH patients treated with 1,25-dihydroxyvitamin D₃ and inorganic phosphate supplementation. Nevertheless, long-term follow-up of kidney function in XLH patients with NC detected ultrasonographically has not been reported. We investigated two women with XLH, ages 31 (patient 1) and 39 (patient 2) years, each of whom had suffered at least one documented episode of vitamin D₂-induced hypercalcemia and renal azotemia during childhood. Patient 2 had also been treated with inorganic phosphate. No medications for XLH had been taken during adulthood. Renal ultrasonography at our institution demonstrated marked bilateral medullary NC in both women. No other explanation was found for their NC that apparently occurred several decades earlier from medical therapy for XLH. Detailed studies (including creatinine clearance, β₂-microglobulin excretion, and fasting urinary osmolality and acidification) revealed no impairment of kidney function in either patient. Our findings indicate that subradiographic medullary NC acquired during medical therapy for XLH may persist for decades, but with no adverse renal sequelae. Definitive (long-term) assessment of kidney function in the XLH population with NC, however, will be necessary to fully understand the risk of current medical treatment for this most common heritable form of rickets.     

微量血25—（OH）D3及相关指标在婴幼儿佝偻病诊断中的评价

探讨婴幼儿维生素Ｄ缺乏性佝偻病的早期诊断。方法应用微量末稍血测定血清２５－（ＯＨ）Ｄ３和相关指标,对２４８名０－３岁儿童进行调查。结果２５－（ＯＨ）Ｄ３、ＡＬＰ、ＡＬＰ３无性别差异,在每半年一个龄龄组分组中,以０－６月龄组婴幼儿的２５－（ＯＨ）Ｄ３最低,而ＡＬＰ、ＡＬＰ明显升高。     

合肥郊区0—6岁儿童营养状况分析

目的：了解合肥郊区儿童的营养状况,评价农村儿保工作的质量。方法：于1990－1995年按既定诊断标准逐年调查全区0－6岁儿童佝偻病、缺铁性贫血（IDA）及营养不良的患病情况。结果;全区儿童营养不良、佝楼病及IDA的患病率分别为0.25％－1.06％,5.72％－18.44％及8．33％－42.9％;1992－1995年营养不良患病率有逐年下降的趋势,而佝偻病及贫血则相反;婴幼儿较学龄前儿童佝偻病患病情况严重,而贫血则相反;男女童营养状况无差异;经济状况较好的近郊儿童的营养状况明显好于经济状况较差的远郊儿童。结论：农村儿保工作的重点仍应放在营养缺乏病的防治上．对婴幼儿重点在佝偻病,学龄前儿童重点在IDA。     

Evidence for vitamin D-independent active calcium absorption in newborn piglets

Summary The role of 1,25-dihydroxycholecalciferol (calcitriol) for intestinal calcium (Ca²⁺) absorption was studied in newborn (<1 week old) and weaned piglets (>6 weeks old). In both groups, normal piglets and piglets suffering from inherited pseudo vitamin D-deficiency rickets, type I (PVDRI) were used. In this inherited disorder, renal production of calcitriol is absent. Plasma samples were assayed for calcitriol and total Ca, and dissociation constants (K_d) and maximum binding capacities (B_max) of intestinal calcitriol receptors were determined under equilibrium conditions at 4°C. Unidirectional Ca²⁺-flux rates were measured across stripped duodenal mucosae in Ussing chambers in the absence of electrochemical gradients. The plasma calcitriol concentrations of neonatal (26.5±7.1 pg/ml, n=11; ± SEM) and weaned PVDRI piglets (18.8±5.7 pg/ml, n=8)were unphysiologically low and differed significantly from control animals (83.6±14.8 pg/ml, n=8, and 86.9±9.6 pg/ml, n=11, respectively). However, newborn PVDRI piglets had normal plasma Ca levels at least during the first days of life. They became hypocalcemic and developed clinical symptoms of rickets during the following weeks. In newborn PVDRI and control piglets, B_max was significantly lower (84±28 fmol/mg protein and 127±55 fmol/mg protein, n=9, respectively) than in weaned piglets (741±82 fmol/mg protein, n=9, and 778±121 fmol/mg protein, n=8, respectively). Significant net Ca²⁺-fluxes were found in both newborn PVDRI and control piglets (88.8±25.1 nmol · cm^-2 · h^-1, n=6, and 86.5±10.5 nmol · cm⁻² · h⁻¹,n=9, respectively). However, active net Ca²⁺ absorption was completely absent in weaned PVDRI piglets. These results indicate the presence of vitamin D-independent mechanisms for active intestinal Ca²⁺ absorption during early postnatal life in pigs.     

小儿骨源性碱性磷酸酶检测结果浅析

目的：探讨骨源性碱性磷酸酶（NBAP）测定在小儿佝偻病早期诊断中的应用价值。方法：随机抽取儿童保健门诊3-36个月婴幼儿400例进行骨源性碱性磷酸酶（NBAP）检测，并对37例中、重度佝偻病患儿NBAP的阳性例数与血清钙、手腕骨x线影像学改变检出例数进行比较。结果：400例婴幼儿NBAP阳性率为31．5％，37例中、重度小儿佝偻病患者中NBAP阳性例数与血清钙、X线影像学改变检出例数相比，差异均具有统计学意义（P〈0．01）。结论：NBAP检测对婴幼儿佝偻病的诊断具有一定的灵敏性和特异性，且检测方便，对小儿佝偻病的早期诊断具有重要意义。     

维生素D和钙剂治疗营养性佝偻病疗效的Meta分析

目的：采用Meta分析对联合补充钙剂、维生素D与单用维生素D或钙剂治疗佝偻病疗效进行定量评价。方法检索Cochrance Library、Pubmed、Web of science、Scirus、中国期刊全文数据库、中国生物医学文献数据库和万方数据库,检索时间均从建库至2013年3月。获得维生素D和钙剂治疗营养性佝偻病相关的RCT文献。选取血清25-( OH)维生素-D3、磷、ALP作为主要测量指标,选取钙、甲状旁腺素、白蛋白、影像评分作为次要测量指标。采用Review Manage 5．0．2对纳入的RCT文献进行Meta分析。结果共检索到437篇文献,对符合纳入标准的3篇文献(n=218)进入Meta分析。 Meta分析结果显示：(1)血清25-(OH)维生素 D3上升程度：联合治疗组与维生素 D 组 MD =-7．88(95%CI：-12．24~-3．52);联合治疗组与钙剂组MD=-18．32(95%CI：-22．61~-14．04);(2)血清磷上升程度：联合治疗组与维生素D组MD=-0．64(95%CI：-0．86~-0．42);联合治疗组与钙剂组MD=-0．16(95%CI：-0．84~0．51);(3)血清 ALP 下降程度：联合治疗组与维生素 D 组 MD =109．99(95%CI：20．40~199．58);联合治疗组与钙剂组MD=59．89(95%CI：10．09~109．59)。(4)血清钙上升程度：联合治疗组与维生素D组MD=-0．71(95%CI：-0．91~-0．52);影像学评分下降程度：联合治疗组与维生素D组MD=0．68(95%CI：0．42~0．95)。以上指标除联合治疗组与钙剂组对血清磷的上升程度差异无统计学意义外,其余差异均具有统计学意义。结论维生素D联合钙剂长期联合治疗佝偻病的疗效要优于单用维生素D或钙剂。     

Screening for Metabolic Bone Disease of prematurity

Metabolic bone disease (MBD) of prematurity remains a significant comorbid condition in preterm, low birth weight infants. As the majority of in utero calcium (Ca) and phosphorus (Phos) accretion occurs during the third trimester, many of these children have inadequate mineral stores and are at risk for deficiencies of Ca and Phos. While fortification of formula has allowed for increased mineral delivery to premature infants, intestinal immaturity prevents optimal absorption. This is compounded by immobilization, delayed establishment of enteral feeds, long term parenteral nutrition and medications that may alter mineral levels. Over time, biochemical changes occur and accompany MBD, with poor bone mineralization during this period increasing the risk for complications such as osteopenia, rickets and fractures. Screening is largely based on risk factors, but despite the 2013 AAP Consensus Statement, there remains significant variation in screening practices across institutions. A combination of laboratory and radiologic testing is often used to diagnose and manage MBD of prematurity, but there exists a lack of consensus on which screening tests and thresholds to use. This is in part related to a lack of normative data and clinical trials for preterm infants, and a result, a lack of evidence-based guidelines on the diagnosis and timing of potential treatment. Biochemical markers, such as serum Phos, alkaline phosphatase (ALP) and parathyroid hormone (PTH), have shown some benefit in the diagnosis of MBD in some studies, but have not always been reproducible. Radiographs may identify different degrees of skeletal changes, but these changes may not be detected until later in MBD development. Other modalities, such as DXA and ultrasound, have also been used, but these may be limited by lack of standards in preterm infants or lack of availability in some centers. Further research, more specifically clinical trials, are needed to determine which combination of tests can detect MBD at its earliest, in order to promote early treatment and prevent short- and long-term complications of MBD.     

Vitamin D deficiency rickets and allegations of non-accidental injury

Vitamin D deficiency rickets has long been recognized as a cause of fractures and fracture-like appearances in young children. Often seen in the early 20th century, rickets has recently been regarded as uncommon; the radiological appearances, familiar to previous generations, may not be recognized for what they are.
This article reports four children with unexplained fractures initially attributed confidently to non-accidental injury. In each case, the later evidence of vitamin D deficiency led to a reconsideration of that diagnosis.
Conclusion:  It is important to be aware of this bone disorder in the differential diagnosis of fractures, to investigate appropriately and to recognize that the radiological appearances may be misleading. A mistaken diagnosis of abuse does real harm, not least to the child itself.     

Rickets with alopecia-remission following a course of 1-α-hydroxy vitamin D3 therapy

A child is described with rickets and alopecia who did not respond to high doses of vitamin D₃ but who responded to a small dose of 1--hydroxyvitamin D₃. Treatment was continued for 2 years and then stopped. She has not shown any signs of relapse 1 year after stopping treatment. Her alopecia, however, has remained unchanged. One year after stopping treatment, her serum 25-hydroxycholecalciferol and parathormone levels were within normal limits but serum 1,25-dihydroxycholecalciferol was elevated.Abbreviations 25 OH D₃ 25-hydroxycholecalciferol - 1,25 (OH)₂ D₃ 1,25-dihydroxycholecalciferol - 1--OH D₃ 1--hydroxy vitamin D - VDDR II vitamin D dependent rickets type II