Vitamin D Insufficiency
Vitamin D hormone production declines markedly
if 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 are
in short supply, a condition often described by terms such
as “vitamin
D insufficiency” or,
if more pronounced, “vitamin D deficiency”. Therefore,
measurement of 25-hydroxyvitamin D levels in blood has become
the accepted method among healthcare professionals to monitor
vitamin D status.
Vitamin D insufficiency is nearly ubiquitous
in the chronic kidney disease (CKD) population. Recent
studies have documented that the great majority of CKD patients
have low blood levels of 25-hydroxyvitamin D, suggesting that
the onset of CKD is a significant risk factor for vitamin D
insufficiency and that the prevalence of vitamin D insufficiency
increases as CKD progresses. In addition, recent studies
have linked vitamin D insufficiency to progression of CKD and
increased morbidity and mortality in hemodialysis patients.1
Market
Opportunity
Vitamin D insufficiency
has been shown to exacerbate the development of secondary hyperparathyroidism
(SHPT) and related bone disease (renal osteodystrophy). Published
sources indicate that 70% of Stage 3, 80% of Stage 4, and 90%
of Stage 5 patients suffer from vitamin D insufficiency. There
are currently over 7.7 million Stage 3 and 4 CKD patients,
and over 472 000 Stage 5 patients in the U.S.2
Parallel advances
in the understanding of vitamin D insufficiency and its complications
have resulted in a new global initiative known as Kidney Disease:
Improving Global Outcomes (KDIGO). The forthcoming new guidelines
from KDIGO are expected to strongly advocate the treatment
of vitamin D insufficiency in CKD patients with SHPT, along
with the more widely accepted vitamin D replacement hormone
therapy for SHPT in CKD patients.
Currently in the U.S., there
are only two options available for the prevention and treatment
of vitamin D insufficiency: Over-the-counter
(OTC) dietary supplements which typically contain 400 to 5,000
IU per unit dose of either vitamin D2 or D3,
and prescription oral products (Drisdol® and
generics) containing 50,000 IU per unit dose of vitamin D2.
Recent studies have shown that both therapies have limited
efficacy in restoring adequate vitamin D prohormone levels.
1. Wolf et al. “Vitamin D levels
and early mortality among incident hemodialysis patients”.
Kidney International (2007) 72, 1004–1013;
2. NKF 2002 K/DOQI
Clinical Practice Guidelines for Bone Metabolism and Disease
in Chronic Kidney Disease, U.S. Renal Data System 2007 Annual
Data Report.
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