Submitted to: Calcified Tissues International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/1995
Publication Date: N/A
Citation: Interpretive Summary: Glycogen storage disease type 1a is a rare genetic condition in which the patient's body uses sugar in an abnormal way. This condition also affects how minerals such as calcium are used. These abnormalities can lead to patient symptoms of varying nature and severity. Problems reported for people with this disease include growth failure, hypoglycemia, and severe osteoporosis. The clinical feature of osteoporosis, a serious brittle-bone disease that can involve life-threatening fractures, provoked interest in tracing the path of dietary calcium in the body to find out how it is deposited and retained in the bones of these patients. We used a new model to make a comparison between the way in which calcium is used by the bodies of healthy people compared to patients with this disease. Special techniques developed at the Children's Nutrition Research Center and elsewhere helped in showing that calcium is used differently by people with hthis disease. The information produced by this analysis will be useful in furthering scientists' understanding of the disease, performing future studies and ultimately finding better ways to help those afflicted.
Technical Abstract: Glycogen storage disease type 1a (Von Gierke's disease) is one of the more common glycogen storage diseases (GSD). GSD 1a patients can have severe idiopathic osteopenia, often beginning at a young age. Since calcium tracer studies offer a sensitive probe of the bone microenvironment and of calcium deposition, kinetics might be disturbed in patients with GSD 1a. Plasma dilution kinetics obtained using the stable isotope 42Ca are shown in this paper to be quite different between GSD 1a patients and age-matched controls. Comparison of kinetic parameters in these two populations is made using a new binding site model for describing calcium dynamics at the plasma-bone interface. This model describes reversible binding of calcium ions to postulated short-term and long-term sites by a retention probability density function psi(t). Using this analysis, adult GSD subjects exhibited a significant decrease (P=0.023) in the apparent half- life of a calcium ion on the longer-term site compared with controls. The general theory of calcium tracer dilution kinetics is then discussed in terms of a new model of short-term calcium homeostasis recently proposed by Bronner and Stein (5).