Kinetic analysis of the rapid intraoperative parathyroid hormone assay in patients during operation for hyperparathyroidism.
BACKGROUND
Rapid intraoperative parathyroid hormone (RI-PTH) assay is used to guide adequacy of resection during operation for hyperparathyroidism. We compared the RI-PTH assay (15 minutes) with a standard PTH assay, determined whether the PTH half-life varied between patients, and constructed a kinetic analysis of the RI-PTH data.


METHODS
Forty-five patients with hyperparathyroidism had blood sampled at baseline and at times after parathyroid resection. Intact PTH was determined using RI-PTH and a standard assay. Values were fitted to an exponential decay curve using the baseline and the follow-up time points. PTH half-life and the new postexcision baseline value were calculated from the decay curve.


RESULTS
The RI-PTH assay and the standard PTH assay correlated well. Average PTH half-life was 1.68 +/- 0.94 minutes (0.42 to 3.81 minutes). A kinetic analysis yielded a formula for the generation of a PTH decay curve. Using a 50% reduction in RI-PTH at 5 minutes as the criterion for adequate resection, 2 patients were incorrectly classified as not being cured. These patients were correctly classified using the kinetic analysis.


CONCLUSIONS
PTH half-life can vary substantially. A kinetic analysis may be more accurate in assessing adequacy of resection. This method allows the surgeon to interpret RI-PTH data independent of the timing of samples.
Libutti
S K
SK
National Institutes of Health, Bethesda, Md. 20892, USA.
Alexander
H R
HR
Bartlett
D L
DL
Sampson
M L
ML
Ruddel
M E
ME
Skarulis
M
M
Marx
S J
SJ
Spiegel
A M
AM
Simmonds
W
W
Remaley
A T
AT
D000328:Adult; D000465:Algorithms; D002624:Chemistry, Clinical / Q000379:methods / Q000592:standards; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D006961:Hyperparathyroidism / Q000097:blood* / Q000601:surgery*; D007118:Immunoassay; D007432:Intraoperative Period; D007700:Kinetics; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D016105:Parathyroidectomy; D012016:Reference Values; D013997:Time Factors
D010281:Parathyroid Hormone