Urinalysis
Gross haematuria is considered unusual in
patients with pyelonephritis and should prompt
exclusion of other diagnoses such as renal calculi,
vasculitis or trauma (Fulop and Mena 2012).
Dipstick urinalysis testing for the presence
of elevated levels of leucocytes, indicative of
infective illness, may be a useful screening
tool for pyelonephritis, but is not specific
enough to make a diagnosis (Mehnert-Kay
2005, Fulop and Mena 2012). Some clinicians
advocate the use of urine dipstick analysis in
combination with urine culture to establish
diagnosis of pyuria (Ramakrishnan and Scheid
2005). Others suggest that routine culture of
urine is unwarranted because a provisional
diagnosis may be achieved by history taking
and urinalysis, and that culture of urine should
only be considered in those who fail to respond
to treatment (Mehnert-Kay 2005). It has been
noted that fever and leucocytosis are of little
diagnostic value in patients with indwelling
urinary catheters because these patients are at
increased risk of developing chronic infection
(Ramakrishnan and Scheid 2005).
Other more specialised investigative
techniques have been recommended,
particularly where diagnosis is challenging.
The presence of urinary interleukin-6 has been
found to be effective in distinguishing between
lower and upper urinary tract infections,
with higher levels indicating upper tract
infection (Rodríguez et al 2008). Retrospective
dimercaptosuccinic acid (DMSA) scanning
of the kidney has shown that children with
pyelonephritis have significantly higher levels
of urinary macrophage migratory inhibitory
factor (a urine-based inflammatory marker)
than those without pyelonephritis (Otukesh
et al 2009). Estimation of levels of procalcitonin
(PCT) is thought to be useful in distinguishing
renal involvement in urinary tract infection
in paediatric patients; urine infection is more
common in this age group and reporting of
symptoms in the pre-verbal and young child
may not yield the quality of information
necessary for diagnosis (Nikfar et al 2010).