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Oral calcium-loading test in infancy, with particular reference to idiopathic hypercalcaemia
Insights
A new oral calcium-loading test aids in diagnosing idiopathic hypercalcaemia in infants. This test is more sensitive than fasting calcium levels for detecting the condition and guiding therapy.
Area of Science:
- Pediatric Endocrinology
- Clinical Chemistry
- Nutritional Science
Background:
- Idiopathic hypercalcaemia in infants presents diagnostic challenges.
- Standard serum calcium measurements may not always detect the condition accurately, especially in milder cases or during fasting.
- A reliable diagnostic tool is needed to assess calcium absorption and disease activity.
Purpose of the Study:
- To describe a novel oral calcium-loading test suitable for infant use.
- To define the typical response to this test in healthy infants.
- To evaluate the test's efficacy in diagnosing idiopathic hypercalcaemia and monitoring treatment.
Main Methods:
- An oral calcium-loading test was administered to infants.
- Serum calcium levels were monitored following oral calcium administration.
- Responses were compared between infants with idiopathic hypercalcaemia and healthy controls.
- The test's utility in assessing disease activity and guiding therapy was assessed.
Main Results:
- The oral calcium-loading test demonstrated a high and sustained rise in serum calcium in acute idiopathic hypercalcaemia cases, suggesting hyperabsorption.
- Milder cases showed an exaggerated response to the loading test even with normal fasting calcium levels, indicating higher sensitivity.
- Abnormal loading tests were observed in patients on treatment or with discontinued treatment who relapsed, correlating with disease activity.
- Test normalization was associated with full recovery, while persistent abnormalities indicated a poor prognosis.
Conclusions:
- The oral calcium-loading test is a sensitive diagnostic tool for idiopathic hypercalcaemia in infants, outperforming fasting serum calcium measurements.
- The test effectively indicates disease activity and serves as a valuable guide for therapeutic interventions.
- Abnormalities in the calcium-loading test can predict long-term prognosis in affected infants.
Abstract:
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.