Risk factors for secondary hyperparathyroidism in a nursing home population.
OBJECTIVE
Secondary hyperparathyroidism may cause bone loss and structural deterioration of bone and may thus be a cause of fracture in the elderly. Vitamin D deficiency, renal impairment and medications are potential causes of hyperparathyroidism and may also directly predispose to fracture. We present the first findings of an ongoing study of hip fracture, vitamin D deficiency and hyperparathyroidism in a large Australian nursing home.


METHODS
Descriptive prevalence study.


METHODS
Two hundred and fifty-one nursing home residents were eligible for inclusion. Informed consent and successful venepuncture were obtained for 99. Residents were of median age 83 years with interquartile range (IR) 77-89 years.


METHODS
25-Hydroxyvitamin D (25OHD), intact parathyroid hormone (PTH), creatinine and biochemistry, demographic data and current medications.


RESULTS
Fifty-two per cent of 99 subjects had 25OHD below the reference range of 28-165 nmol/l and 96.5% were below the reference range mean. Those with low 25OHD had lower plasma calcium corrected for albumin than those with normal 25OHD (medians 2.34 vs 2.41 mmol/l, 95% confidence interval for the difference between medians (CI) -0.10 to -0.04 mmol/l, P = 0.0001) and higher PTH (medians 5.8 vs 3.9 pmol/l, CI 0.10-2.6 pmol/l, P = 0.0360). Twenty-eight per cent of 97 residents had PTH above the upper reference range limit of 6.5 pmol/l. Residents receiving frusemide had higher PTH than other residents (medians 6.95 vs 3.45 pmol/l, CI 1.9-4.2 pmol/l, P < 0.0001). In linear modelling, the most important predictor of the natural logarithm of PTH was daily frusemide dose, adjusted R2 (Ra2) = 31.8%, F = 39.3, P < 0.001. Creatinine and the reciprocal of 25OHD were other significant predictors with the final Ra2 = 39.4%, F = 17.7, P < 0.001.


CONCLUSIONS
Vitamin D deficiency is a common risk factor for secondary hyperparathyroidism in nursing home residents despite a climate in which vitamin D nutrition is thought to be ample. However, the daily frusemide dose is a more important predictor of PTH in this population.
Stein
M S
MS
Department of Medicine, University of Melbourne, Victoria, Australia.
Scherer
S C
SC
Walton
S L
SL
Gilbert
R E
RE
Ebeling
P R
PR
Flicker
L
L
Wark
J D
JD
D015652:25-Hydroxyvitamin D 2 / Q000172:deficiency*; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia; D002118:Calcium / Q000097:blood; D005260:Female; D005665:Furosemide / Q000009:adverse effects; D006620:Hip Fractures / Q000209:etiology; D006707:Homes for the Aged; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000097:blood / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009735:Nursing Homes; D010281:Parathyroid Hormone / Q000097:blood; D012307:Risk Factors; D012709:Serum Albumin / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications*
D010281:Parathyroid Hormone; D012709:Serum Albumin; D015652:25-Hydroxyvitamin D 2; D005665:Furosemide; D002118:Calcium