An article published in the Journal of Bone and Mineral Metabolism suggests that unexplained flank pain may be due to a vitamin D deficiency. If there is no medical history of kidney problems, trauma, etc., and no positive radiology findings, you can try supplementing with vitamin D, and you have about a 50% chance of finding relief within 2 months. ~ Dr. Broussard
Journal of Bone and Mineral Metabolism
September 2018, Volume 36, Issue 5, pp 605–608
Abstract
Loin pain is frequently not associated with any urinary abnormality. Musculoskeletal abnormalities are not uncommon as alternative cause of flank pain. Osteomalacia of the ribs was infrequently encountered as the cause of flank pain. Vitamin D deficiency has been reported as a common problem worldwide with special predilection to the Middle East area. In this study, we looked for vitamin D deficiency in patients with flank pain associated with tenderness over the tips of the lowermost ribs. Out of 783 patients presenting with unilateral or bilateral flank pain to a single center over a period of 3 years, 316 did not have a definite urologic cause (group B). One hundred and eighty-seven of these patients had distinct tenderness over the costal margin (group B1) that could not be explained by history and radiology. All patients of group B were tested for serum levels of 25(OH) vitamin D. Very low serum levels of 25(OH) vitamin D was detected in all cases of group B1 and in only in only 26.4% of the remaining cases of group B (group B2). Relief of flank pain was noticed within 2 months in 55.1% of vitamin D deficient cases. In patients presenting with flank pain, the existence of tenderness of the last ribs instead of the renal angle proper should alert to a possible cause in the rib cage. Estimation of serum vitamin D level should be performed in these cases.