title: Demography and biochemistry of 2800 patients from a renal stones clinic.
abstract: BACKGROUND
  Because the causes of stones are uncertain, interventions to prevent recurrence have an insecure foundation. Progress depends on careful evaluation of stone formers.
  
  
  METHODS
  A descriptive retrospective database study of 1983 men and 816 women from the Southampton stones clinic from 1990 to March 2007. Anonymized data from the first attendance were analysed using non-parametric statistical tests.
  
  
  RESULTS
  Sex ratio (2.43:1), age (median 49 y, 2.5th-97.5th percentiles, 23-77 y men, 20-79 y women), recurrent stone formers (30%) and type of stone were similar to other centres. Women more often had a positive family history (24% versus 19% men), previous urinary infection (31% versus 5%) and structural urinary tract abnormality (14% versus 7%); more men had gout (5% versus 1%) and bladder outlet obstruction (3% versus <1%). Calcium, oxalate and uric acid excretion were increased in 43%, 17% and 22% respectively of men and 31%, 7% and 10% of women. Urinary calcium, oxalate and uric acid correlated significantly, r ranging from 0.149 to 0.311 for 24 h excretion and 0.510 to 0.695 for concentrations per litre. Twenty-two percent of men and 8% of women with normal parathyroid hormone had phosphaturia (excretion of phosphate corrected for glomerular filtration rate (TmPO4/GFR) < 0.70 mmol/L); 6% men and 1.6% women also had low plasma phosphate. Many variables correlated significantly but often weakly with age. Creatinine clearance, pH and (men) TmPO4/GFR decreased from 50 y, urine creatinine, calcium and citrate from 60 y.
  
  
  CONCLUSIONS
  Risk factors for stones differ between men and women, change with ageing and in some may have a genetic basis. The role of phosphaturia merits further exploration.
authors: Department of Clinical Biochemistry, Southampton University Hospitals NHS Trust, C Level MP 6, South Block, Tremona Road, Southampton SO16 6YD, UK. valerie.walker@uhs.nhs.uk
authors: Valerie
authors: V
authors: Walker
authors: Elizabeth M
authors: EM
authors: Stansbridge
authors: Damian G
authors: DG
authors: Griffin
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000097:blood / Q000378:metabolism / Q000652:urine; D000554:Ambulatory Care Facilities; D003710:Demography; D005260:Female; D006801:Humans; D007015:Hypophosphatemia, Familial / Q000150:complications; D007669:Kidney Calculi / Q000097:blood / Q000453:epidemiology* / Q000378:metabolism* / Q000652:urine; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012727:Sex Characteristics; D055815:Young Adult