The prognosis in idiopathic hypercalcaemia of infants

Vitamin D deficiency in surgical congenital heart disease: prevalence and relevance

Vitamin D is a pleiotropic hormone important for the proper functioning of multiple organ systems. An emerging body of adult and pediatric critical care literature strongly suggests that vitamin D deficiency contributes to secondary organ pathophysiology, prolongs ICU stay, and worsens outcome in critically ill populations. Recent clinical studies suggest that a significant number of children with congenital heart disease (CHD) have post-operative vitamin D deficiency which appears to be associated with greater cardiovascular dysfunction. Altogether the cumulative body of literature suggests that peri-operative optimization of vitamin D status has the potential to speed recovery and/or improve outcome. This review describes the epidemiological and basic science research linking vitamin D deficiency to post-operative organ dysfunction. Furthermore, the available supplementation approaches are reviewed in the context of prevention of post-operative vitamin D deficiency and avoidance of toxicity in the majority of CHD patients. Finally, knowledge gaps regarding vitamin D supplementation are identified and the next stages for research are outlined.

Involvement of claudin 3 and claudin 4 in idiopathic infantile hypercalcaemia: a novel hypothesis?

BACKGROUND

Idiopathic infantile hypercalcaemia (IIH) is a rare disease that generally resolves spontaneously between the age of 1 and 3 years. Similar symptoms may occur in patients suffering from Williams-Beuren syndrome (WBS), which is caused by a microdeletion on chromosome 7. Two of the genes, named CLDN3 and CLDN4, located within this region are members of the claudin family that has been shown to be involved in paracellular calcium (Ca(2+)) absorption. Based on the hemizygous loss of CLDN3 and CLDN4 in WBS and the function of these genes in paracellular Ca(2+) transport, we hypothesized that mutations in CLDN3 or CLDN4 could also be involved in IIH.

METHODS

Biochemical characteristics, including calciotropic hormone levels, were obtained from three typical IIH patients. CLDN3 and CLDN4 sequences were also analysed in these patients. The major intestinal Ca(2+) transporter TRPV6 was also screened for the presence of mutations, since hypercalcaemia in IIH and WBS has been shown to result from intestinal hyperabsorption. All three patients were also analysed for the presence of deletions or duplications using a single-nucleotide polymorphism (SNP) array for genomic DNA.

RESULTS

The serum Ca(2+) levels of patients were 2.9, 3.3 and 3.8 mmol/L (normal <2.7 mmol/L). Levels of 25-hydroxyvitamin D(3) and 1,25-dihydroxyvitamin D(3) were normal, parathyroid hormone (PTH) and PTH-related peptide (PTHrP) levels were appropriately low. Sequencing of coding regions and intron-exon boundaries did not reveal mutations in CLDN3, CLDN4 and TRPV6. Identified SNPs were not correlated with the disease phenotype. A SNP array did not reveal genomic deletions or duplications.

CONCLUSIONS

Biochemical analysis did not reveal inappropriate levels of calciotropic hormones in IIH patients in this study. Furthermore, based on the lack of mutations in CLDN3, CLDN4 and TRPV6, we conclude that IIH is neither caused by mutations in these candidate genes nor by deletions or duplications in the genome of these patients.

Idiopathic infantile hypercalcaemia--a continuing enigma

Seventy six children with documented Fanconi-type idiopathic infantile hypercalcaemia were studied and compared with 41 with the Williams-Beuren syndrome. Clinical comparison showed, as expected, very close similarities but also considerable differences, particularly in the severity of feeding problems and the degree of failure to thrive. The estimated incidence of idiopathic infantile hypercalcaemia alone has remained constant for the past 20 years, at approximately 18 cases per year in the United Kingdom (1 per 47 000 total live births). Long term morbidity in these children is mainly due to mental handicap and arteriopathy, but hypertension (29%), kyphoscoliosis (19%), hyperacusis (75%), and obesity (50%) may be added complications. In one child, hypercalcaemia recurred during adolescence but this seems to be excessively rare. More detailed investigation before treatment is required to discover the aetiology of hypercalcaemia in this condition.

Oral calcium-loading test in infancy, with particular reference to idiopathic hypercalcaemia

An oral calcium-loading test suitable for infants is described and the usual response defined. In four acute cases of idiopathic hypercalcaemia a high and sustained rise in serum calcium occurred, suggestive of hyperabsorption and consistent with a vitamin-D-like effect. In four further infants with a milder illness suggestive of hypercalcaemia the fasting calcium levels were not grossly raised, but the test produced an exaggerated hypercalcaemic response. In this type of patient the test is more sensitive in the diagnosis of idiopathic hypercalcaemia than isolated measurements of serum calcium, especially if these are taken in the fasting state. Five patients on treatment and three whose treatment had been discontinued (but who subsequently relapsed or made a poor recovery) showed abnormal loading tests at a time when fasting calcium levels were normal. In two cases full recovery from the disease was associated with reversion of the test to normal. The test can therefore be used to indicate activity of the disease and consequently as a guide to therapy. In two cases a persistently abnormal loading test was associated with a poor long-term prognosis.

[IDIOPATHIC HYPERCALCEMIA IN THE CHILD: 2 NEW CASES AND REVIEW OF THE LITERATURE]

Several reports of idiopathic hypercalcemia of childhood have been published since Lightwood in 1932 described dwarfism associated with mental retardation, strabismus, hypercalcemia, nephrocalcinosis and osteosclerosis. The present paper adds two new cases. The first patient was 15 months old when first seen with stunted physical and mental growth, a systolic murmur, and a serum calcium value of 13 mg. %. This child suffered several severe infections and in spite of a low calcium intake and the administration of chelating agents her blood calcium rose until death six months later. The other patient, three years old, also had delayed physical and mental development, typical facies, a systolic murmur, skeletal lesions, and nephrocalcinosis. Varied therapeutic attempts failed.Idiopathic hypercalcemia of childhood is reviewed in the light of the 94 reports already published.