Osteoporosis Complicating Renal Tubular Acidosis in Association With Sjogren's Syndrome

Chronic metabolic acidosis increases alkali mobilization from the bone and promotes the development of osteoporosis. We report the case of a 35-year-old Caucasian female who presented for surgical fixation of a left femoral fracture sustained six months previously from a ground level fall with known primary hypothyroidism (for 12 years, on thyroxine replacement) with history of hypokalemia for the last 13 years (on regular oral potassium supplements). There was no history of fracture in past. There was no history of renal stones. There was positive history of hypokalemic periodic paralysis twice in past (12 and 13 years back). There was no history of recurrent oral or ocular ulcers. On examination there was no uveitis, oral ulcers, lacrimal or parotid gland enlargement. Upon workup the patient was diagnosed with left-sided femur fracture (neck) and was admitted for surgical management. She underwent left dynamic hip screw fixation under general anesthesia which she tolerated well. Upon further workup she had normal anion gap with hyperchloremic metabolic acidosis, low vitamin D level and dual-energy x-ray absorptiometry (DEXA) scan revealed osteoporosis at femur and hip joint. Vitamin D was replaced, she was started on Ibandronate and calcium supplements. Her further workup revealed positive anti-SSA. Our final clinical diagnosis in this case is possible or incomplete Sjogren's syndrome causing type-1 renal tu­bular acidosis (RTA; distal RTA) with osteoporosis.