dipstick - saonew

[ArchivalUser]

A patient with lymphoma who is known to excrete
1.5 g urinary protein per day has a negative dipstick evaluation
for urinary protein. The reason for the seeming
inconsistency is
(A) the size of the excreted protein is too small to be
picked up by the test strip
(B) the urine is not concentrated enough
© only heavy chain sequences are recognized by the
test strip
(D) Tamm-Horsfall protein blocks the reaction between
the secreted protein and the test strip
(E) dipsticks preferentially detect albumin compared
with immunoglobulin because albumin is negatively
charged

[ArchivalUser]

e??

[ArchivalUser]

EE??

[ArchivalUser]

The answer is E. Up to 150 mg/d of protein may be excreted by a normal person. The bulk of normal daily excretion is made up of the Tamm-Horsfall mucoprotein.
Urine dipsticks may register a trace result in response to as little as 50 mg protein per liter
and are definitively positive once the urine protein exceeds 300 mg/L. A false negative
may occur if the proteinuria is due to immunoglobulins, which are positively charged. If
proteinuria is suspected or documented, a 24-h urine collection should be undertaken to
measure the absolute protein excretion. Urine immunoelectrophoresis also may identify
the particular immunoglobulin that is produced in excess.