title: Mathematical formulation to help identify the patient at risk of ischemic tissue necrosis--a potentially lethal complication of chronic renal failure.
abstract: Ischemic tissue necrosis (ITN) has been described as a complication of hyperparathyroidism (HPT) in patients with end-stage renal disease (ESRD) and is associated with a mortality rate of up to 80%. Early recognition of ITN is important but difficult. Optimal treatment is controversial. Based on an analysis of the English literature and a recent clinical experience, a mathematical expression to aid in the identification of high-risk patients (2 x [CaPO(4) - 5] x alkaline phosphatase x PTH ratio) was developed. The values for this expression were calculated in 3 recently reported cases and our case (n = 4). The values were compared with those of a group of 54 hyperparathyroid chronic hemodialysis patients (controls); the mean values were significantly different (p < 0.001). The expression, consisting of 4 easily measured laboratory values, appears to differentiate patients with this complication of ITN from patients with only severe HPT. Ten new additional cases were evaluated using the equation; the sensitivity of the equation was 80% and the specificity 92%, positive predictive value was 66% and the negative predictive value 96%. Long-term validation of this equation is required but it appears to be discriminatory and, thus, promising, given the potentially lethal consequences of ITN.
authors.affiliation: St. Paul's Hospital, Vancouver, B.C., Canada.
authors.forename: A
authors.initials: A
authors.lastname: Levin
authors.forename: R L
authors.initials: RL
authors.lastname: Mehta
authors.forename: M B
authors.initials: MB
authors.lastname: Goldstein
mesh_terms: D000328:Adult; D000469:Alkaline Phosphatase / Q000097:blood; D002115:Calciphylaxis / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D002118:Calcium / Q000097:blood; D002130:Calcium Phosphates / Q000097:blood; D005260:Female; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000209:etiology; D007676:Kidney Failure, Chronic / Q000150:complications*; D008962:Models, Theoretical; D010281:Parathyroid Hormone / Q000097:blood; D011237:Predictive Value of Tests; D012307:Risk Factors; D012680:Sensitivity and Specificity
chemical_list: D002130:Calcium Phosphates; D010281:Parathyroid Hormone; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; D000469:Alkaline Phosphatase; C485829:calcium phosphate, dibasic, anhydrous; D002118:Calcium