Why do I have a burning sensation while passing urine?

Hello doctor,

In recent test reports, the following test values are out of range: Estimated glomerular filtration rate (eGFR) is 83, uric acid is 7.9, serum creatinine is 1.13, blood urea nitrogen (BUN) to serum creatinine ratio is 7.59, 25-hydroxyvitamin D (total) is 8.73, homocysteine is 30, iron 57.8, and red cell distribution width - coefficient of variation (RDW-CV) of 14.6. As far as symptoms are concerned, I am feeling body pains especially stiffened neck and pain in upper shoulders, feeling drowsy in the morning, slight burning sensation near the urinary bladder while passing urine, and a burning sensation in my left calf muscle and foot sometimes. There is a feeling of a lot of gastric problems especially while waking up in the morning and sometimes constipation. I am not on any medicine. The lab reports are attached for your review.

Thank you doctor,

What about the estimated glomerular filtration rate (eGFR) and the creatinine levels? Do these values have any impact on the functionality of the kidneys? Do you suggest any medicine for vitamin D deficiency?