Hypercalcemia, hypercalciuria, medullar nephrocalcinosis, and renal insufficiency in a toddler with Down syndrome

Rare Causes of Hypercalcemia: 2021 Update

CONTEXT

Primary hyperparathyroidism and malignancy are the etiologies in 90% of cases of hypercalcemia. When these entities are not the etiology of hypercalcemia, uncommon conditions need to be considered. In 2005, Jacobs and Bilezikian published a clinical review of rare causes of hypercalcemia, focusing on mechanisms and pathophysiology. This review is an updated synopsis of rare causes of hypercalcemia, extending the observations of the original article.

EVIDENCE ACQUISITION

Articles reporting rare associations between hypercalcemia and unusual conditions were identified through a comprehensive extensive PubMed-based search using the search terms "hypercalcemia" and "etiology," as well as examining the references in the identified case reports. We categorized the reports by adults vs pediatric and further categorized the adult reports based on etiology. Some included reports lacked definitive assessment of etiology and are reported as unknown mechanism with discussion of likely etiology.

EVIDENCE SYNTHESIS

There is a growing understanding of the breadth of unusual causes of hypercalcemia. When the cause of hypercalcemia is elusive, a focus on mechanism and review of prior reported cases is key to successful determination of the etiology.

CONCLUSIONS

The ever-expanding reports of patients with rare and even unknown mechanisms of hypercalcemia illustrate the need for continued investigation into the complexities of human calcium metabolism.

Intractable Vomiting in an 11-Month-Old Boy With Trisomy 21: A Case Report on Abnormal Calcium/Calcinosis/Creatinine in Down Syndrome

Abnormal calcium/calcinosis/creatinine in Down syndrome (ABCD syndrome) is a very rare condition with no clear etiology. In this paper, we describe our clinical encounter with this disease. We report the case of an 11-month-old male infant with Down syndrome (DS) who presented to the hospital with intractable vomiting and decreased oral intake and urine output. The evaluation revealed an acute kidney injury (AKI) and hypercalcemia. Although his AKI improved with intravenous hydration, his hypercalcemia persisted. Extensive studies were notable for an elevated urinary excretion of calcium and bilateral medullary nephrocalcinosis seen on renal ultrasound (US). As a result, he was diagnosed with ABCD syndrome. Dietary calcium restriction was implemented. During his follow-up visit with a pediatric endocrinologist, his serum calcium was found to be normalized. To our knowledge, this is only the seventh case report on ABCD syndrome in the literature.

The A, B, C, D of hypercalcaemia in Down syndrome

Hypercalcaemia in infants with Down syndrome is an uncommon condition with only five previous case reports. The patients often present in the toddler years with the classical triad of Down syndrome, biochemical hypercalcaemia, and nephrocalcinosis. We present the sixth case and second male with this condition and further review the clinical details of this under-recognised condition and stratify the diagnostic criteria. The management mandates a reduction in calcium intake as a first step. The natural history of the various aspects of this condition is also considered.

Nutrient intake and anthropometry in children and adolescents with Down syndrome--a preliminary study

OBJECTIVE

To assess nutrient intake and anthropometrical characteristics of children and adolescents with DS, in Northern Greece.

STUDY DESIGN

Cross-sectional study of 34 youngsters with DS. The sample was divided into two age groups, children aged 2-9 years and adolescents aged 10-18 years old. A 3-day food record was used to assess dietary intake. Body weight, height, WHR,% body fat, BMI, FMI, FFMI and z-scores were recorded for each participant.

RESULTS

All participants exhibited a high CHO and low fat diet. More than half of the participants reported having five meals daily and the majority exercised twice a week. A great majority was stunted and overweight according to general population growth charts and 22% of the adolescents were also obese. %Body fat, BMI, FMI and FFMI was higher in adolescents. Generally, younger participants presented lower overweight rates and consumed a diet more sufficient in micronutrients; however, WHR was similar in both age-groups, indicating a constant trend in weight distribution of DS patients.

CONCLUSIONS

Although children with DS are born with a genetic predisposition to become overweight, obesity is actually nurtured throughout childhood when they develop food choices and become more independent.

Clinical review: Rare causes of hypercalcemia

CONTEXT

Although hypercalcemia is usually caused by primary hyperparathyroidism or malignancy, a number of other conditions can be important to consider. This review considers unusual causes of hypercalcemia that are generally not found in reviews on this subject.

EVIDENCE ACQUISITION

Articles describing rarely reported associations between hypercalcemia and unusual causes were identified through a computer search of the terms hypercalcemia/etiology and through the references listed in those articles. We grouped the 58 different reports into categories defined by a presumed etiology: increased levels of 1,25-dihydroxyvitamin D or PTHrP, occult milk-alkali syndrome, and undefined mechanisms. Reports in infants and children are listed separately, as are reports of pseudohypercalcemia, situations that are not truly hypercalcemic because the ionized calcium is normal.

EVIDENCE SYNTHESIS

In some situations, as this review points out, a number of unusual causes of hypercalcemia are important to consider. The search for an elusive cause of hypercalcemia is best accomplished by the most likely potential mechanism. An orderly search in this manner is likely to reveal the underlying cause.

CONCLUSIONS

That so many patients have been described with rare and usually poorly understood causes of hypercalcemia highlights our incomplete understanding of calcium metabolism in humans and suggests additional areas in which directed clinical investigation might improve our knowledge of the normal metabolism of calcium.

Renal involvement in Down syndrome

Kidney disease has not been considered a frequent complication in Down syndrome (DS) patients; a variety of urological abnormalities and glomerulopathies have been reported in this population, and some DS patients develop chronic renal failure (CRF). The aim of this study was to improve the understanding of renal disease in patients with DS, focusing on the incidence and range of kidney and urological abnormalities in a population of DS patients. A cross-sectional study was carried out in DS patients referred from a pediatric genetics unit of a tertiary care center. Medical records were reviewed. A 24-h urine specimen and a blood sample were obtained. Fractional excretion of sodium and potassium, tubular reabsorption of phosphate, urinary excretion of calcium, magnesium, uric acid, creatinine clearance and proteinuria were determined. Ultrasound was performed to evaluate the kidneys and the urinary tract. Laboratory data were reviewed for any possible renal disorder. Sixty-nine patients, aged 12 months to 24 years, were recruited. Pathological findings included three cases of voiding disturbances and a case of hypertension in a 7-year old girl. Eight patients (11.6%) had hyperuricemia without gout. Eighteen patients (24.2%) had hyperuricosuria. Urinalysis revealed three cases of mild proteinuria and two patients with microscopic hematuria. Minor radiological abnormalities were found in five patients (7.3%). Three patients (4.5%) had CRF. Renal disease in patients with DS is not as rare as previously thought, although the majority of findings are of minor relevance. According to the variety of pathologies, and in order to detect early irreversible renal injury, it seems quite reasonable to perform regular monitoring of renal function in these patients.

Genetic Hypercalciuria

Hypercalciuria is an important, identifiable, and reversible risk factor in stone formation. The foremost and most fundamental step in dissecting the genetics of hypercalciuria is understanding its pathophysiology. Hypercalciuria is a complex trait. This article outlines the various factors that compromise the attempt to dissect the genetics of hypercalciuria, summarizes the clinical and experimental monogenic causes of hypercalciuria, and outlines the initial results from attempts in studying polygenic hypercalciuria. Finally, the problem is set in perspective of the current database, technologic advances and limitations are highlighted, and prospects of further advances in the field are speculated upon.

Hypercalcaemia in association with trisomy 21 (Down's syndrome)

The combination of hypercalcaemia, hypercalciuria, and nephrocalcinosis with and without renal impairment is rare in paediatric clinical practice. However, this constellation of findings has been reported in three children with trisomy 21, but the absence of detailed nutritional data has failed to clarify the underlying pathogenesis. This report describes a 4 year old girl with trisomy 21 who was found coincidentally to have hypercalcaemia, hypercalciuria, nephrocalcinosis, and renal impairment in the absence of metabolic alkalosis, following a prolonged period of excessive calcium intake.