February 1, 2021 Author : Bruno Graça What is renal lithiasis? Renal (in the kidney) and ureteral (in the ureters) lithiasis is the presence of calculus, commonly known as stones , in those urinary tract structures. The stones can have variable dimensions, from millimeter ones - up to 5 mm and are known as sand or microlithiasis - to large stones, which can occupy a large part of the interior of the kidney. The stones present in the ureters are almost always formed in the kidneys and then move to the ureters. However, when they remain in the ureters for an extended period, they can continue to grow. How do stones are formed? The stones are formed by saturation and crystallization of urine salts in the kidney , the organ where urine is produced. Stones can have different composition: Most stones - 75% -80% - have calcium in their composition and are not dissolved by medication. Uric acid stones - 5%-10% of cases - are due to the crystallization of urates in acidic urine. Sometimes, medication to alkalinize urine can promote its dissolution. Struvite stones - phosphate-ammonia-magnesium - are more rare and are produced by bacteria that cause chronic urinary infection. Cystine stones are very hard and are due to an inherited genetic disease. In rare cases, stones are a side effect of medications, for example with indinavir, triamterene or sulfasalazine. Renal colic The displacement of the kidney stones and their migration to the ureters may or may not cause an obstruction to the passage of urine . When there is obstruction, renal colic results. This is characterized by acute and strong low back pain with abdominal irradiation , nausea, vomiting and no relief position. Blood may also appear in the urine and, if there is a concomitant infection, fever and malaise may appear. Renal colic is described as one of the most difficult pains, even worse than labor or burn pains. Its severity depends on the degree and speed of installation of the urine flow obstruction and the location of the stone and not on its dimensions. If the kidney or ureteral stone does not obstruct the flow of urine, the lithiasis will not give symptoms or they will only be mild. Diagnosis Renal colic is a common cause of seeking medical care, often in the emergency room. The diagnosis of renal lithiasis is made based on clinical examination and confirmed through some diagnostic tests, such as urine analysis and renal and bladder ultrasound. When there is still some doubt or if you want to define more precisely the dimensions of the stones and their exact location, it may be necessary to perform a computed tomography (CAT) scan. Metabolic study Some urinary metabolic changes may contribute to the formation of stones . Therefore, in specific situations and not in an emergency context, the diagnosis may include a metabolic study, always in view of optimizing prevention. Metabolic changes are usually investigated in young patients, under the age of 25, or who have recurrent renal colic. The metabolic study is done in a 24-hour urine sample in which various compounds are determined, for example calcium, the hormone that regulates calcium metabolism, uric acid, phosphates, and citrates, among others. When metabolic changes are identified, the involvement of medical specialties such as nephrology or endocrinology may be recommended. Anatomical changes Some anatomical changes can also contribute to the formation of stones , for example the obstruction of the ureteropelvic junction (connection between the kidney and the ureter) or horseshoe kidneys. Therefore, the diagnosis may also involve research in this regard. Treatment of renal lithiasis The t reatment of renal lithiasi s can be urgent when there are alarm symptoms, for example: Uncontrollable pain; Febrile syndrome suggestive of concomitant urinary infection; Dehydration due to nausea and vomiting; Progressive acute renal failure. In other cases, the need to actively treat the stones depends on several factors such as their location, dimensions, symptoms, and the patient preferences. For example, about 80%-85% of ureteral stones are expelled without specific treatment . However, when they are larger than 5 mm, their elimination without treatment becomes less frequent and when the stones reach 10 mm it is practically nil. Learn more about the treatment and prevention of kidney stones . Meet the urology team from Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
