Randall plaque versus renal stone?

Imaging strategies for patients with suspicion of uncomplicated colic pain: diagnostic accuracy and management assessment

OBJECTIVE

Compare different imaging scenarios in the diagnosis of uncomplicated renal colic due to urolithiasis (URCU).

MATERIALS AND METHODS

A total of 206 prospectively included patients had been admitted with suspected URCU and had undergone abdominal plain film (APF), US and unenhanced CT after clinical STONE score evaluation. CT was the reference standard. We assessed sensitivity (Se), specificity (Spe) and Youden index for colic pain diagnosis, percentage of patients managed by urologic treatment with stone identified, percentage of alternative diagnoses (AD) and exposure to radiation, according to single imaging approaches, strategies driven by patient characteristics and conditional imaging strategies after APF and US.

RESULTS

One hundred (48.5%) patients had a final diagnosis of URCU and 19 underwent urologic treatment. The conditional strategy, i.e. CT in patients who had no stone identified at US, had a perfect sensitivity and specificity. This enabled diagnosis of all stones requiring urology management while decreasing the number of CT exams by 22%. The strategy whereby CT was used when there was neither direct or indirect APF + US finding of colic pain nor alternative diagnoses in patients with a STONE score ≥ 10 had a sensitivity of 0.95 and a specificity of 0.99, identified 84% of stones managed by urologic treatment and decreased the number of CT examinations by 76%.

CONCLUSION

In patients with clinical findings consistent with URCU, the use of ultrasound as first-line imaging modality, with CT restricted to patients with negative US and a STONE score ≥ 10, led to a sensitivity and specificity of above 95%, identified 84% of stones requiring urological management and reduced the number of CT scans needed by fourfold.

KEY POINTS

• For diagnosis, the use of APF + US as first-line imaging, with CT restricted to patients with both a normal APF + US and a STONE score ≥ 10, provides both a sensitivity and specificity superior or equal to 95% and reduces the number of CT scans necessary by fourfold. • For management, the use of APF + US as first-line imaging, with CT restricted to patients with both a normal APF + US and a STONE score ≥ 10, maintains a 84% stone identification rate in urology-treated patients.

Determining the true burden of kidney stone disease

The incidence and prevalence of kidney stones have increased over the past four decades. However, the diagnosis of 'kidney stone' can range from an incidental asymptomatic finding of limited clinical significance to multiple painful episodes of ureteral obstruction with eventual kidney failure. Some general strategies may be useful to prevent the recurrence of kidney stones. In particular, greater attention to kidney stone classification, approaches to assessing the risk of recurrence and individualized prevention strategies may improve the clinical care of stone formers. Although there have been some advances in approaches to predicting the recurrence of kidney stones, notable challenges remain. Studies of kidney stone prevalence, incidence and recurrence have reported inconsistent findings, in part because of the lack of a standardized stone classification system. A kidney stone classification system based on practical and clinically useful measures of stone disease may help to improve both the study and clinical care of stone formers. Any future kidney stone classification system should be aimed at distinguishing asymptomatic from symptomatic stones, clinically diagnosed symptomatic stone episodes from self-reported symptomatic stone episodes, symptomatic stone episodes that are confirmed from those that are suspected, symptomatic recurrence from radiographic recurrence (that is, with radiographic evidence of a new stone, stone growth or stone disappearance from presumed passage) and determine stone composition based on mutually exclusive categories.

Calcium oxalate calculi-induced clusterin expression in kidney

The aim of the study was to investigate clusterin expression in the kidney and evaluate the urine clusterin level in the kidney stone formers. (1) In vitro, we treated the Madin-Darby canine kidney (MDCK) cell line with different concentrations of calcium oxalate (CaOx), and then the clusterin protein expression in the cells was evaluated by Western blotting. (2) Kidney stone patients who received percutaneous nephrolithotomy were enrolled in our study. Urine samples were collected before surgery, the kidney punctured to obtain kidney tissue guided by ultrasound intraoperatively. Clusterin expression in the human kidney tissue was evaluated by immunochemistry. The urine clusterin level was determined by enzyme-linked immunosorbent assay. Non-kidney disease subjects were chosen as controls. In vitro, the clusterin expression was up-regulated in the MDCK cells induced by CaOx. The study included 49 patients and 41 non-kidney disease subjects. All calculi were composed of calcium oxalate monohydrate or calcium oxalate dihydrate and a few also contained protein or uric acid. Mean ± SD urine clusterin level was 17.47 ± 18.61 μg/ml in patients, and 3.31 ± 5.42 μg/ml in non-kidney disease subjects, respectively (p < 0.001). Immunohistochemistry revealed the clusterin was located in the cytoplasm of the renal distal and collecting tubular epithelial cells. Also the tissue clusterin expression increased significantly in the kidney stone formers compared to the control groups (p = 0.001). CaOx could induce clusterin expression in renal tubular cells, and increase clusterin levels in the kidney and urine from the kidney stone formers.