I am unable to make a specific diagnosis based on the information that you present. Your father may have early chronic kidney disease (CKD) but I cannot establish the specific kidney disease. In order to establish CKD, he needs to be retested in three months to see if there is any changes in his estimated glomerular filtration rate (eGFR). If the eGFR stays below 60 milliliters per minute per 1.73 meters squared, then he likely has Stage 3 CKD. On the basis of his aging alone, he likely has some reduction in his eGFR. At age 89, his eGFR would normally be about 50 or 60, so most of his reduction could be explained by his age.
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