Falls, impairment of kidney function and vitamin D
We read with interest the clinical review "Fall assessment in older
people" by Close and Lord(1). Among the risk factors for falls, some
authors have included kidney failure and its relation to defective
conversion of calcidiol to calcitriol(2). Vitamin D3 and D2, produced by
photo-synthesis in the skin or ingested, are transported to the liver and
metabolised to 25-hydroxyvitamin D, the major circulating form. Further
hydroxylation occurs in the kidney to form the highly biologically active
1,25-dihydroxyvitamin D. In contrast to the abundant availability of
hepatic 25-hydroxylase, the renal capacity for 1 alfa-hydroxylation is
limited. Already with a creatinine clearance of less than 65 ml/min it is
significantly reduced(3). Impairment of kidney function is very frequent
in the elderly and may be overlooked because normal serum creatinine
levels in most patients. Perhaps, in these patients D-analogs, preferably
alfacalcidol, might be superior in reducing falls in comparison to the
plain vitamin D.
In the AAC-Trial(4) ninety patients were included as
matched triplets to receive randomly either 1 mcg alfacalcidol daily + 500
mg calcium (group A, n = 30) or 70 mg alendronate weekly + 1,000 mg
calcium + 1,000 IU vitamin D daily (group B, n = 30) or 1 mcg alfacalcidol
daily + 70 mg alendronate weekly + 500 mg calcium daily (group C, n = 30).
This study showed that the combination of alendronate and alfacalcidol was
superior in reducing falls in comparison to the combination of alendronate
and vitamin D, but not in comparison to alfacalcidol alone. There were 5
new falls with alfacalcidol versus 11 new falls with alendronate+vitamin D
versus 4 new falls with alfacalcidol+alendronate.
References
1. Close JC, Lord SR. Fall assessment in older people. BMJ
2011;343:d5153.
2. Ringe JD, Schacht E. Potential of alfacalcidol for reducing
increased risk of falls and fractures. Rheumatol Int. 2009;29:1177-85.
3. Dukas LC, Schacht E, Mazor Z, St?helin HB. A new significant and
independent risk factor for falls in elderly men and women: a low
creatinine clearance of less than 65 ml/min. Osteoporos Int 2005;16:332-8.
4. Ringe JD, Farahmand P, Schacht E, Rozehnal A. Superiority of a
combined treatment of Alendronate and Alfacalcidol compared to the
combination of Alendronate and plain vitamin D or Alfacalcidol alone in
established postmenopausal or male osteoporosis (AAC-Trial). Rheumatol Int
2007;27:425-34.
Rapid Response:
Falls, impairment of kidney function and vitamin D
We read with interest the clinical review "Fall assessment in older people" by Close and Lord(1). Among the risk factors for falls, some authors have included kidney failure and its relation to defective conversion of calcidiol to calcitriol(2). Vitamin D3 and D2, produced by photo-synthesis in the skin or ingested, are transported to the liver and metabolised to 25-hydroxyvitamin D, the major circulating form. Further hydroxylation occurs in the kidney to form the highly biologically active 1,25-dihydroxyvitamin D. In contrast to the abundant availability of hepatic 25-hydroxylase, the renal capacity for 1 alfa-hydroxylation is limited. Already with a creatinine clearance of less than 65 ml/min it is significantly reduced(3). Impairment of kidney function is very frequent in the elderly and may be overlooked because normal serum creatinine levels in most patients. Perhaps, in these patients D-analogs, preferably alfacalcidol, might be superior in reducing falls in comparison to the plain vitamin D.
In the AAC-Trial(4) ninety patients were included as matched triplets to receive randomly either 1 mcg alfacalcidol daily + 500 mg calcium (group A, n = 30) or 70 mg alendronate weekly + 1,000 mg calcium + 1,000 IU vitamin D daily (group B, n = 30) or 1 mcg alfacalcidol daily + 70 mg alendronate weekly + 500 mg calcium daily (group C, n = 30). This study showed that the combination of alendronate and alfacalcidol was superior in reducing falls in comparison to the combination of alendronate and vitamin D, but not in comparison to alfacalcidol alone. There were 5 new falls with alfacalcidol versus 11 new falls with alendronate+vitamin D versus 4 new falls with alfacalcidol+alendronate.
References
1. Close JC, Lord SR. Fall assessment in older people. BMJ 2011;343:d5153.
2. Ringe JD, Schacht E. Potential of alfacalcidol for reducing increased risk of falls and fractures. Rheumatol Int. 2009;29:1177-85.
3. Dukas LC, Schacht E, Mazor Z, St?helin HB. A new significant and independent risk factor for falls in elderly men and women: a low creatinine clearance of less than 65 ml/min. Osteoporos Int 2005;16:332-8.
4. Ringe JD, Farahmand P, Schacht E, Rozehnal A. Superiority of a combined treatment of Alendronate and Alfacalcidol compared to the combination of Alendronate and plain vitamin D or Alfacalcidol alone in established postmenopausal or male osteoporosis (AAC-Trial). Rheumatol Int 2007;27:425-34.
Competing interests: None declared
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