Calciolactia is most often defined as a cystic fluid filled with calcium in a renal cyst or sometimes in a fluid-filled calyx. Renal calciolactia is not common in clinical practice and most people have never heard of it. A more familiar term is renal cyst, which is a benign lesion of the kidney with a cystic fluid in the middle and usually does not contain calcium; if the cystic fluid is filled with calcium, it is called calciolactia, which is only one of the manifestations of calciolactia. Another type of calcemia is when there is fluid in the calyces, and the fluid also contains calcium, which is called hydronephrosis. Some patients may have recurrent urinary tract infections, such as fever, back pain, frequent urination, urgency, painful urination, and bloody urine in the naked eye. If there are no symptoms and they are relatively small, they can be dynamically reviewed. If there are recurrent symptoms of urinary tract infection, surgical removal should be considered in addition to antibiotic anti-infection treatment.