on 20 Sep 99, Eric Kilpatrick wrote...
>We have a 30 year old lady who apparently has been hypocalcaemic for the=20
>last 10 years. Typically, her total calcium is 1.8 mmol/L, phosphate 1.2=
>=20
>mmol/L, albumin 42 g/L, magnesium 0.8 mmol/L. Her PTH is usually=20
>low/low-normal, and the working diagnosis has been idiopathic=20
>hypoparathyroidism. However, she has been unresponsive to vitamin D=20
>treatment and has had several admissions for =91fits=92 which have been a=
>ssumed=20
>to be tetanic. Her total calcium has never adequately responded to calci=
>um=20
>or vitamin D supplements. Her urinary calciums have always been within ou=
>r=20
>reference interval. Her episodes of tetany also appear to have a function=
>al=20
>element to them.
>
>Last week she had ionised calcium measured by a gas analyser and this was=
>=20
>found to be 1.52 mmol/L which would, if anything, suggest she is=20
>hypercalcaemic. It now transpires that her mother has also been found to =
>be=20
>'hypocalcaemic' although she is asymptomatic.
>
>Of course, the ionised calciums are going to be repeated, but I would be=20
>grateful if anyone has any ideas on this case.
>
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>
Dear Eric
You may have a case of Autosomal Dominant Hypocalcaemia with Hypercalciuria
(ADHH), which is caused by inappropriate activation of the calcium receptor due
to a mutation in the receptor gene (CaR). These patients typically have
detectable PTH, Calcium/Creatinine clearance ratio >0.15 and fail to respond
to calcium and vitamin D supplements which only cause hypercalciuria and renal
stones (therefore avoid). This information was gleaned from a CME review in the
Journal of RCP London last year by a Professor Stewart who is interested in the
gene. I gave my only copy away to a colleague last week! I'll get you the
reference ASAP.
************************************
Home Address:
Dermot Neely
52 Albert St
Durham
DH1 4RJ Tel. 0191-384 6125
Work Address:
Dr R.D.G.Neely BSc MD FRCP FRCPath
Department of Clinical Biochemistry
Dryburn Hospital
North Road
Durham
DH1 5TW Tel. 0191-333 2440
Fax. 0191-333 2679
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