Urinalysis

Dipstick urinalysis profile of an asymptomatic female group in south-east Nigeria

Objectives:

Routine dipstick urinalysis is a useful and inexpensive method for the early detection of asymptomatic diseases. Our study was carried out to detect the prevalence of urinary abnormalities among an apparently asymptomatic healthy female group and emphasize the value of routine dipstick urinalysis.

Methods:

A cross-sectional study was carried out among second to sixth (final)-year female medical students of Nnamdi Azikiwe University, Nnewi campus between 8 and 30 September 2019. A total of 100 subjects were enrolled. First-morning midstream urine samples were collected and promptly tested with dipstick strips. Subjects with abnormal findings were informed and treated appropriately.

Results:

In all, 54 (54%) of the subjects had urine abnormalities. Trace proteinuria was the commonest abnormality seen with a prevalence of 33%, followed by abnormal urine appearance (17%), leucocytes (14%), nitrites (8%) and urobilinogen (2%). Urine abnormalities were commoner in students who resided in the school hostel. Abnormal urine appearance was significantly associated with nitrites (0.003) and leucocytes (0.001).

Conclusion:

Routine dipstick urinalysis should be performed among students and apparently healthy individuals for early detection and diagnosis of renal diseases to facilitate quick interventions and prevent further progression.

Urinary Squamous Epithelial Cells Do Not Accurately Predict Urine Culture Contamination, but May Predict Urinalysis Performance in Predicting Bacteriuria

OBJECTIVES

The presence of squamous epithelial cells (SECs) has been advocated to identify urinary contamination despite a paucity of evidence supporting this practice. We sought to determine the value of using quantitative SECs as a predictor of urinalysis contamination.

METHODS

Retrospective cross-sectional study of adults (≥18 years old) presenting to a tertiary academic medical center who had urinalysis with microscopy and urine culture performed. Patients with missing or implausible demographic data were excluded (2.5% of total sample). The primary analysis aimed to determine an SEC threshold that predicted urine culture contamination using receiver operating characteristics (ROC) curve analysis. The a priori secondary analysis explored how demographic variables (age, sex, body mass index) may modify the SEC test performance and whether SECs impacted traditional urinalysis indicators of bacteriuria.

RESULTS

A total of 19,328 records were included. ROC curve analysis demonstrated that SEC count was a poor predictor of urine culture contamination (area under the ROC curve = 0.680, 95% confidence interval [CI] = 0.671 to 0.689). In secondary analysis, the positive likelihood ratio (LR+) of predicting bacteriuria via urinalysis among noncontaminated specimens was 4.98 (95% CI = 4.59 to 5.40) in the absence of SECs, but the LR+ fell to 2.35 (95% CI = 2.17 to 2.54) for samples with more than 8 SECs/low-powered field (lpf). In an independent validation cohort, urinalysis samples with fewer than 8 SECs/lpf predicted bacteriuria better (sensitivity = 75%, specificity = 84%) than samples with more than 8 SECs/lpf (sensitivity = 86%, specificity = 70%; diagnostic odds ratio = 17.5 [14.9 to 20.7] vs. 8.7 [7.3 to 10.5]).

CONCLUSIONS

Squamous epithelial cells are a poor predictor of urine culture contamination, but may predict poor predictive performance of traditional urinalysis measures.

Does lower urine-specific gravity predict decline in renal function and hypernatremia in older adults exposed to psychotropic medications? An exploratory analysis

BACKGROUND

Exposure to psychotropic agents, including lithium, antipsychotics and antidepressants, has been associated with nephrogenic diabetes insipidus (NDI). This is especially concerning in older adults already at risk of developing chronic kidney disease (CKD) and hypernatremia with advanced aging. This study investigates whether commonly performed random urine-specific gravity (USG) tests can predict adverse NDI outcomes (CKD and hypernatremia) in psychotropic-exposed older adults.

METHODS

This was a retrospective longitudinal study of 173 geriatric psychiatry patients (age ≥65 years) exposed to psychotropic medications. Our main continuous outcome was 'decrease in estimated glomerular filtration rate (eGFR) >10 mL/min/1.73 m(2)' over 5-year follow-up. Hypernatremia and acute kidney injury (AKI) were secondary outcomes. Whether baseline USG <1.010 predicted outcomes was assessed in bivariate and multivariate analyses.

RESULTS

USG <1.010 predicted hypernatremia episodes (sodium concentration ≥150 mmol/L-28.1 versus 12%, χ(2) = 4.7, P = 0.03). USG <1.010 [odds ratio 2.36 (95% confidence interval 0.93-6.0), P = 0.07], baseline eGFR and typical antipsychotic use independently predicted decrease in eGFR >10 mL/min/1.73 m(2). Patients with a single baseline sodium concentration of ≥140 mmol/L and USG <1.010 have a 26.3% incidence of AKI and a 57.9% incidence of hypernatremia over the ensuing 5 years.

CONCLUSIONS

In psychotropic-exposed older adults, there appears to be a clinically important association between low USG and developing both hypernatremia and CKD. USG may be a useful surrogate measure for NDI-related outcomes in large administrative database studies, where ideal measures such as 24-h urine volume may not be available.

The McGill Geriatric Lithium-Induced Diabetes Insipidus Clinical Study (McGLIDICS)

OBJECTIVE

Despite being a common and potentially serious condition, nephrogenic diabetes insipidus (NDI) remains poorly understood in older lithium users. Our main objective was to compare the prevalence of NDI symptoms and decreased urine osmolality ([UOsm] < 300 milli-Osmoles [mOsm/kg]) among geriatric and adult lithium users. We also assessed NDI symptoms, serum sodium (Na+), and urine specific gravity (USG) as possible surrogate measures of decreased UOsm, and ascertained whether potential etiologic factors independently correlated with decreased UOsm.

METHOD

This was a cross-sectional study of 100 consecutive outpatients treated with lithium from 6 tertiary care clinics, of which 45 were geriatric (aged 65 years and older) and 55 adult (aged 18 to 64 years). Patients completed a symptom questionnaire and underwent laboratory tests, including UOsm, serum Na+, and USG.

RESULTS

Geriatric and adult lithium users had similar rates of decreased UOsm (12.5%, compared with 17.9%, P = 0.74), but geriatric patients reported less symptoms (P < 0.05). Although UOsm did not correlate with symptoms or current serum Na+, USG of less than 1.010 was suggestive of UOsm of less than 300 mOsm/kg. Age, lithium duration, and serum lithium level were independently associated with UOsm.

CONCLUSIONS

The prevalence of decreased UOsm is similar in geriatric and adult lithium users, but older patients are less likely to report urinary and thirst symptoms. Although subjective symptoms do not correlate with UOsm, USG may be a cost-efficient clinical surrogate measure for UOsm. We suggest clinicians increase their vigilance for decreased UOsm, especially in lithium users with advanced age, longer duration of lithium exposure, and higher lithium levels. This may potentially prevent lithium intoxication, falls, hypernatremic events, and renal dysfunction.

Squamous cells as predictors of bacterial contamination in urine samples

STUDY OBJECTIVE

To determine whether squamous cells in urine indicate bacterial contamination.

METHODS

We prospectively studied 105 consecutive women who presented to the emergency department with symptoms suggestive of a urinary tract infection. Two urine samples were collected from each woman, a midstream clean-catch (MSCC) sample and a catheterized (CATH) sample. Microscopic urinalyses to assess for squamous cells and urine cultures to assess for bacterial contamination were performed on all samples. Bacterial contamination was defined as growth of fewer than 10,000 colonies of a single species per milliliter or growth of three or more species of commensal bacteria (mixed flora) in a urine sample.

RESULTS

Squamous cells were found in 99 of 105 CATH samples (94%); however, no CATH samples had bacterial contamination. Squamous cells were found in 101 of 105 MSCC samples (96%); however, only 22 MSCC samples (21%) had bacterial contamination.

CONCLUSION

The presence of squamous cells in CATH urine samples obtained from women is not indicative of bacterial contamination. The presence of squamous cells in MSCC urine samples obtained from women also is not a good indicator, with an overall predictive value for bacterial contamination of 21%.

Suprapubic bladder aspiration versus urethral catheterization in ill infants: success, efficiency and complication rates

STUDY OBJECTIVE

To compare success rates, complications, and efficiency of suprapubic bladder aspiration with urethral catheterization in ill infants.

DESIGN

Prospective, randomized clinical study.

SETTING

The pediatric emergency department at the University of Mississippi Medical Center in Jackson.

PARTICIPANTS

Convenience sample of infants under 6 months of age requiring an uncontaminated urine specimen for the evaluation of febrile illness, suspected urinary tract infection, or sepsis. Infants with wet diapers were excluded.

INTERVENTIONS

Patients were randomized to undergo timed suprapubic bladder aspiration (performed by a physician and a nurse) or urethral catheterization (performed by two nurses). If suprapubic bladder aspiration was unsuccessful, urethral catheterization was performed immediately and the bladder was drained; emptying volume was recorded. All patients had a next-void "bag" urinalysis performed for post-procedure hematuria.

RESULTS

Fifty patients underwent primary suprapubic bladder aspiration. The success rate (defined by obtaining at least 2 mL of urine) was 46%. Mean +/- SD time per successful suprapubic bladder aspiration was 16.73 +/- 7.73 seconds. Fifty patients underwent primary urethral catheterization. The success rate was 100%; the mean time required was 80.70 +/- 46.52 seconds. After failed suprapubic bladder aspiration, urethral catheterization was 100% successful, with a mean draining volume of 2.95 +/- 2.38 mL. No immediate problems were identified among any instrumented patients; later complications (next-void hematuria after either procedure, other visceral injury with suprapubic bladder aspiration) were not detected.

CONCLUSION

Both suprapubic bladder aspiration and urethral catheterization afford the emergency physician low-risk access to uncontaminated urine in ill infants. Suprapubic bladder aspiration is less efficient in that it requires physician participation and failure rates are higher. These data suggest that successful suprapubic bladder aspiration is primarily dependent on the volume of urine in the bladder; thus, in the ill or febrile ED infant who may be dehydrated, the likelihood of success decreases. The authors recommend that ED nursing and physician staff become comfortable with performing urethral catheterization on infants.

The place of routine urine testing on admission to hospital

An audit of routine urine testing by dipsticks at a large private provincial hospital analysed 2294 patient records. No result was recorded in 12% of records. Abnormal but expected results were obtained in 9% of cases. Of the 4% of unexpectedly abnormal results, in only one-third of patients was the attending practitioner aware of these results and, in fewer than one-fifth of the patients, were further diagnostic tests performed. In not one case was treatment altered.

Urine sampling in ambulatory women: midstream clean-catch versus catheterization

We conducted a study to determine if there were any significant differences in urinalyses or urine cultures obtained by midstream clean-catch (MSCC) urine sampling in comparison with in-and-out catheterization (CATH). One hundred five women with symptoms suggestive of a urinary tract infection were studied prospectively. Each woman had a MSCC urine sample obtained initially, followed by a CATH sample. The MSCC and CATH urine samples were analyzed and compared for urine culture, leukocyte esterase, nitrites, microscopic bacteriuria, and pyuria. Of the 105 patients, 42 (40%) had a culture-proven urinary tract infection. The concordance rates between MSCC and CATH urine cultures, nitrites, leukocyte esterase, significant microscopic bacteriuria, and pyuria were 96%, 94%, 93%, 90%, and 90%, respectively. There were no statistically significant differences between MSCC and CATH sensitivities, specificities, or positive or negative predictive values for any urinalysis variable (leukocyte esterase, nitrites, significant microscopic bacteriuria, or pyuria). We conclude that if proper MSCC technique is used, the differences between MSCC and CATH urinalyses or urine cultures do not appear to be significant in the majority of ambulatory women without active vaginal bleeding who present with symptoms suggestive of a urinary tract infection.