Pregnancy builds the danger of first-time symptomatic kidney stone

Pregnancy builds the danger of first-time symptomatic kidney stone


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  • Source: Mayo Clinic

  • Date: 15 Apr,2021

Though researchers have long known that several physiological and anatomical changes occur during pregnancy which could contribute to kidney stone formation, evidence of the connection has been lacking.

An observational study that reviewed the medical records for nearly 3,000 female patients from 1984 to 2012 finds that pregnancy increases the risk of a first-time symptomatic kidney stones. The risk peaks near delivery and then improves by one year following delivery, though a small risk of developing kidney stones lasts beyond one year after delivery.

The analysis, published in the American Journal of Kidney Diseases, included 945 women who underwent a first-time symptomatic kidney stone and 1,890 age-matched female control subjects. The study’s goal was to determine whether the risk of a first-time symptomatic kidney stone increased with pregnancy and if the risk varied across different time intervals before, during and after pregnancy.

We suspected the risk of a kidney stone event would be high during pregnancy, but we were surprised that the risk remained high for up to a year after delivery. There also remains a slightly increased risk of a kidney stone event beyond a year after delivery. This finding implies that while most kidney stones that form during pregnancy are detected early by painful passage, some may remain stable in the kidney undetected for a longer period before dislodging and resulting in a painful passage.”

Andrew Rule, M.D., Mayo Clinic Nephrologist and Study’s Senior Author

A symptomatic kidney stone occasion has become the most common nonobstetric hospital admission diagnosis for pregnant women. A symptomatic kidney stone event occurs in 1 of every 250-1,500 pregnancies, research shows, most often occurring during the second and third trimesters. Kidney stones, though uncommon, can cause significant complications, ranging from preeclampsia and urinary tract infection to preterm labor and delivery, and pregnancy loss.

Diagnosis of kidney stones during pregnancy can be challenging, given limited diagnostic imaging alternatives because of concern about radiation exposure, says Dr. Rule. Treatment can be complicated by obstetric concerns, as well.

Several physiological reasons may contribute to why pregnancy contributes to kidney stone formation, says Charat Thongprayoon, M.D., a Mayo Clinic nephrologist and the study’s corresponding author. During pregnancy, ureteral compression, and ureteral comfort as a result of elevated progesterone hormone can cause urinary stasis in the body. Additionally, increased urine calcium excretion and elevated urine pH during pregnancy can result in calcium phosphate stone formation.

Awareness of a higher risk of kidney stones during pregnancy and the postpartum period can help healthcare providers offer diagnostic and preventive strategies for girls.

“Urinary obstruction due to kidney stones can lead to pain that some patients describe as the worst pain they have ever experienced,” says Dr. Thongprayoon. “During pregnancy, a kidney stone may contribute to serious complication, and the results of this study indicate that prenatal counseling regarding kidney stones may be justified, especially for women with other risk factors for kidney stones, such as obesity.”

Mayo Clinic specialists also recommend appropriate calcium intake during pregnancy of at least 1,000 milligrams every day, preferably from dietary sources such as dairy products as opposed to calcium supplements.

The study examined data from the Rochester Epidemiology Project, a collaboration of practices, hospitals and other health care facilities in Minnesota and Wisconsin, and community members that have agreed to discuss their health records for research. This project enables vital research that may discover causes, treatments, and cures for disease.

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