Nephrolithiasis and/or nephrocalcinosis (management and evaluation)

The following guideline has been developed by Clinicians within the Renal Unit, Yorkhill. This document is intended for use by clinicians in the Management and Evaluation of Nephrolithiasis/Nephrocalcinosis.

Nephrolithiasis or renal stone disease remains a significant health problem in the adult population but the frequency in childhood is much less. The term nephrocalcinosis (NC) implies an increase in calcium content in the kidney and may coexist with nephrolithiasis. NC occurs less frequently than nephrolithiasis and may be focal, occurring in an area of previously damed parenchyma or generalised usually as a result of underlying metabolic disorder in which it is most prominent in the renal medulla. In practice the commonest cause of NC is associated with pre term delivery where the aetiology is likely to be related to the hypercalciuric effect of loop diuretic therapy perhaps in combination with corticosteroids and Methylxanthines. Other causes are hypercalcaemic states, e.g. hyperparathyroidism, vitamin D intoxication, prolonged immobilisation, idiopathic hypercalcaemia and tumour related hypercalcaemia.

The incidence and aetiology of renal stones differs significantly amongst different geographical regions. In European children infection related stones predominate and these are located in the upper urinary tract and are composed of struvite (magnesium, ammonium, calcium phosphate) and are frequently related to proteus UTI. Hypercalciuria is the most common metabolic cause of stones in Western children but no diagnosis is determined in around a third of patients. North American data of analysed stones suggest the frequency and composition of urinary tract stones as:

• Calcium oxalate 70-80%
• Calcium phosphate 5-10%
• Uric acid 5-10%
• Struvite 5-10%
• Cystine 1-5%

NC is generally asymptomatic unless associated with nephrolithiasis and the latter presents with abdominal or flank pain, micro/macroscopic haematuria and UTI.

Evaluation of patient with NC and nephrolithiasis is similar:

1. Ultrasound and abdominal x-ray
2. Biochemical stone analysis when possible. If the biochemical stone analysis suggests a cystine stone, the key investigation is urinary amino acid chromatography. If analysis suggests a uric acid stone the key investigations are urinary urate creatinine ratio, plasma urate, plasma HGPRT and APRT. If analysis suggests a struvite stone, metabolic evaluation is unnecessary.
3. If the biochemical stone analysis suggests calcium oxalate/calcium phosphate or if there is no stone recovered, the following investigations should be carried out.

• Should any aspect of this guideline change before the planned review date in August 2007, a full review of this document should be undertaken.
• Future review of this guideline will incorporate the AGREE document designed to ensure that the clinical questions identified within this guideline incorporates the most up to date evidence and best clinical practice. For further information on guideline development please contact the Multi-Professional Clinical Practice Committee Chairperson.

Calcium (Male and Female)

Urate (Male and Female)

Oxalate (Male and Female)