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Is
There a Role for Routine Phosphate Testing in Patients Using Tenofovir?
Tenofovir
disoproxil fumarate/TDF (Viread) has been anecdotally associated with
isolated hypophosphatemia
(HP) as well as proximal
tubular toxicity and renal
dysfunction in which HP has consistently been a feature.
Consequently, routine phosphate measurements in TDF recipients have
been recommended.
British
researchers identified and compared the frequency of HP in TDF recipients
with that in non-TDF recipients; assessed the reproducibility of
HP; identified the incidence of renal dysfunction in hypophosphatemic
patients; and evaluated associations between HP and host, HIV infection,
or treatment factors.
This
prospective observational study measured serum phosphate, urea,
and creatinine
in HIV-positive individuals among the following treatment groups:
TDF-containing highly active antiretroviral therapy (HAART, group
A), TDF-sparing HAART (group B), HAART naive (group
C), and off HAART but treatment experienced (group D).
Results
· Phosphate
measurements were obtained in 252 patients. Seventy-two percent
of patients prescribed TDF received a phosphate measurement.
· The
frequency of HP in groups A, B, C, and D was 31%, 22%, 10%, and
14%, respectively.
· Kaletra
use and duration of antiretroviral therapy were independently associated
with HP, but elevated creatinine and urea or use of TDF was not.
The
authors conclude, “The etiology of HP seems to be multifactorial
and unrelated to TDF or renal dysfunction. This questions the utility
of routine phosphate testing, in isolation, in TDF recipients.”
Brighton and Sussex University Hospitals,
National Health Service Trust, Brighton, Sussex, United Kingdom.
03/25/05
Reference
S
L Day and others. Serum hypophosphatemia in tenofovir disoproxil
fumarate recipients is multifactorial in origin, questioning the
utility of its monitoring in clinical practice. Journal
of Acquired Immune Deficiency Syndromes 38(3): 301-304. March
1, 2005.
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