ESSENTIALS OF DIAGNOSIS
Renal colic is classically described as a waxing and waning pain, which starts in the flank and may radiate to the groin. It may be accompanied by hematuria.
An ultrasound is an appropriate first test to diagnose a kidney stone, a helical non-contrast CT scan—either low dose or standard dose may also be considered.
Chemical analysis of the stone is very helpful in determining further treatment.
Individuals with multiple stones, very early age of onset of stones, or multiple risk factors should undergo further metabolic workup to determine appropriate treatment for stones.
Kidney stones are becoming more common and are associated with significant morbidity. The overall prevalence of kidney stones has increased from 3.8% of the population in 1976–1980 to 8.8% of the population in 2007–2010 based on NHANES data. Non-Hispanic white men have the highest prevalence of stones, followed by Hispanic men, non-Hispanic white women, and Hispanic women. Non-Hispanic black men and women have the lowest prevalence of stones at 4.8% and 4.2% respectively.
Nutritional factors also play a role in the development of kidney stones. Diets rich in magnesium, potassium and calcium with good fluid intake decrease the risk of kidney stones while diets high in fructose, sucrose, or sodium with low fluid intake increase risk of kidney stones. Being overweight or obese increases the risk for a kidney stone in both men and women. Lower household income also increased risk of developing a kidney stone. Stones are more common in warmer climates.
An initial evaluation of a kidney stone patient should include a detailed medical history. Bowel disease leading to chronic diarrhea and malabsorption increases risk of kidney stones. Bariatric surgery (Roux-en-Y gastric bypass), small bowel resection, and ileostomy will increase risk. Systemic diseases which increase urine or serum calcium will also increase risk and include primary hyperparathyroidism and sarcoidosis. Certain medications, such as topiramate and carbonic anhydrase inhibitors will increase risk. Diabetes, gout, and hyperthyroidism will increase risk of kidney stones.
Certain occupations may also increase risk of kidney stones (Table 39–1). For example, taxi cab drivers, who have infrequent access to restrooms, are at higher risk, as are those who work in hot environments or with infrequent access to fluids.
Table 39–1.Specific concerns for stone formers which increase risk for recurrent stones. ||Download (.pdf) Table 39–1. Specific concerns for stone formers which increase risk for recurrent stones.
| ||Metabolic Risk ||Stone Type |
|Inflammatory bowel disease or chronic diarrhea ||hyperoxaluria ||Calcium oxalate |
|Intestinal surgery, including ileostomy or colectomy ||Volume depletion, bicarbonate loss ||Calcium oxalate or uric acid |
|Roux-en-Y, gastric bypass ||hyperoxaluria ||Calcium oxalate |
|Sarcoidosis, primary hyperparathyroidism, immobilization, hyperthyroidism ||Hypercalciuria ||Calcium phosphate and calcium oxalate stones |
|Distal renal tubular acidosis ||Low urine citrate but high urine pH...|