Clin Endocrinol (Oxf). 2017 Sep 26. doi: 10.1111/cen.13486. [Epub ahead of print]
Farrell CL1, Nguyen L1, Carter AC1.
1 Department of Clinical Chemistry, Laverty Pathology, 60 Waterloo Rd, North Ryde, NSW 2113, Australia.
PTH does, however, vary with the level of Vitamin D
Wonder what % of the increase in PTH with age is due to the decrease in level of Vitamin D with age.
- Primary Hyperparathyroidism perfectly predicted with a Vitamin D-Based nomogram – Nov 2011
has the following equation which agrees that there is an increase with age
PTH (pg/ml) = 120- (6 × calcium (mg/dL))- (0.52 × 25-hydroxy vitamin D (ng/ml)) + (0.26 × patient age (years)).
Age-related changes in parathyroid hormone (PTH) have been previously documented in adults. However, because of the limitations of traditional approaches to establishing reference intervals, age-related reference intervals have not been defined. We sought to use a data mining approach to derive age-related PTH reference intervals.
DESIGN AND PARTICIPANTS:
Results from patients undergoing PTH testing over a 4 year period were extracted from the database of a private pathology laboratory in New South Wales, Australia. Patients were included in the study if they were 18 years or older and had simultaneous determination of PTH, serum calcium, estimated glomerular filtration rate and 25-hydroxyvitamin D (25-OHD). Patients with abnormalities of serum calcium or renal function were excluded.
Bhattacharya analysis of log transformed data was used to derive age-related PTH reference intervals across adulthood.
Results were available for 33,652 subjects. Among patients with optimal 25-OHD status, older age was associated with higher PTH concentrations. Age-related reference intervals were derived and showed a 63% increase in the upper and lower reference limits between the youngest (18 - 29 years of age) and the oldest (80 years of age or older) age partitions. The appropriateness of using a single reference interval for patients of all ages was evaluated against objective criteria and was found to be unsatisfactory.
Data mining was demonstrated to be a useful tool for establishing age-related PTH reference intervals. The technique demonstrated that increasing age is associated with higher PTH concentrations and that age-related reference intervals are important for accurate result interpretation.