At 2000-09-29 23:04 +0200, Silvia Gracia wrote:
>I would like to know what methods are your labs using for renal stone
>analysis?
Unfortunately good methods for renal stones are expensive. Many labs
performe X-ray chrystallography but, by definition, this method can only
give information regarding the chrystalline components of the stones.
Most (80-90 %) renal stones are composed of mixtures of calcium phosphates
(apatites, calcium hydrogen phosphate, and amorphous calcium phosphate) and
calcium oxalates (whewellite, weddelite).
Infection stones are formed in alkaline urine and they usually contains
magnesium ammonium phosphate (struvite), carbonate apatite and other
calcium phosphates. Traces of ammonium urate can also be found in such stones.
Stones caused by hyperoxaluria contains almost pure calcium oxalate
(weddellite) without any trace (<1%) of phosphate.
Bladder stones are mainly composed of uric acid and may contain ammonium urate.
Cystin stones are usually pure cystin.
Beside these components traces of proteins, matrix and water are included.
An interesting component is Lithofibrin, a macromolecular
probably polyaromatic heterocyclic substance, which may be the nucleating
factor for the first (calcium phosphate + calcium oxalate) type of renal stone.
The best method for renal stone analysis is wet chemistry because no other
method is sufficiently sensitive to minor (<10%) or non-chrystalline
components.
c.f. Larsson et al: Clin Chim Acta 1984:140:9-20
Öhman & Larsson: Acta Chem Scand 1996;50:633-6
Sten Öhman, PhD
Elfin Lab & Milieuconsult
P O Box 133
S-590 70 Ljungsbro
Sweden
Tel Nat: 013-368940 Int: +46 13 368940
Fax Nat: 013-368941 Int: +46 13 368941
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