Stone Analysis (FT-IR)

Description: 
The stone unit based at Guy’s Hospital is one of the largest in the country. It has state of the art treatment options including a dedicated operating theatre for patients with stones, which is used five days a week. There are 1,700 inpatient admissions at Guy's Urology with a further 900 stone unit admissions. GSTT runs the UK’s only service for an inherited kidney stone disease, cystinuria.

The stone analysis service in Reference Chemistry is complemented by metabolic investigations in the Inherited Metabolic Disease laboratory (urine amino acids for cystine, ornithine, arginine and lysine) and genetic/molecular investigations in the Purine Research Laboratory (APRT/HPRT mutations) within Biochemical Sciences. The Genetics laboratory based at Guy's Hospital offers cystinuria genetics.

Stone analysis is performed to determine the chemical composition of a stone submitted to the laboratory and is very important in the understanding of pathophysiology, choice of treatment modality and prevention of recurrences. A fully quantitative assessment is obtained by Fourier Transform Infra Red (FT-IT) Spectroscopy. FT-IR is a specific, rapid and versatile method that uses infra red radiation that cause atomic vibrations, consequently, energy absorption and finally, appearance of absorption bands in the IR spectrum of stone sample. Attenuated reflective technology (ATR) is used for infra red analysis of stone and unknown materials.
Clinical details: 
Nephrolithiasis (stone formation in kidneys) is a recurrent condition with significant morbidity. While symptomatic episodes require appropriate treatment, prophylactic work up to prevent recurrence is of great importance.

Stone formation is governed by both intrinsic (heredity, age & sex) and extrinsic factors (geography, climate, water intake & diet). Calcium-containing calculi account for 30-90% of all renal stones. They are most commonly idiopathic in origin but hypercalcaemia, especially that of primary hyperparathyroidism, should be excluded as a cause. Uric acid stones account for a further 10% of renal calculi. Rare causes are cystinuria and hyperoxaluria.

Stones along the urinary tract can be located in the kidneys, ureters and urinary bladder. Stones in the renal pelvis or urethra are of particular clinical significance because of their frequent association with serious renal disease or as the aetiologic agent of renal colic.
Reference range: 

Stone components are reported in percentage (%). Stone macroscopic and microscopic descriptions also provided in the report.

Sample type and Volume required: 
Stone material collected in a plain universal container.
Turnaround time: 
7 working days.
Special sample instructions: 

None.

Storage and transport: 
First Class post.
Contacts:
Reference Chemistry Laboratory at St Thomas'
020 7188 1264
4th floor, North Wing
St Thomas' Hospital
Westminster Bridge Road
London SE1 7EH
For clinical advice or interpretation of results, please contact the laboratory in the first instance.

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Last updated: 10/11/2015