Recalcitrant Leg Pain In A Runner

HISTORY: A 21 year old female runner and former collegiate field hockey player with a history of typhoid in 2018 complicated by residual bowel issues s/p cholecystectomy and bilateral grade 1 tibial bone stress injuries 1 year ago presented with bilateral shin pain for 3 weeks. She noticed the pain after a 2 hour run. Pain in bilateral shins was 3/10 and worse with standing and exercise. Her menstrual cycles were normal over the past year, after a history of dysregulation for 2 years. She saw a sports nutritionist and adjusted her diet to include adequate caloric intake for her activity. PHYSICAL EXAMINATION: Examination revealed tenderness to palpation of the right middle third of the tibia and left distal third of the tibia. Normal light touch sensation, and full strength in bilateral lower extremities. Normal ankle range of motion and gait. Able to do double and single leg jumps without pain. DIFFERENTIAL DIAGNOSIS:1. Bilateral tibial stress fractures2. Medial tibial stress syndrome3. Chronic exertional compartment syndrome TEST AND RESULTS: Recalcitrant bilateral grade 1 tibial stress fractures in setting of increased calcium excretion after cholecystectomy post typhoid infection FINAL WORKING DIAGNOSIS: MRI of the right lower leg: minimal periosteal edema along proximal right tibial shaft, Grade I Fredericson criteria. DEXA: Whole body Z-score 0.4, AP spine Z-score -0.2, Left femoral neck Z-score 1.0, Left total hip Z-score 1.0 (normal) Vitamin D, 25-Hydroxy level: 24.8 (insufficient) 24 hour urine collection, Calcium: 516 (elevated, in Feb), 195.8 (normal, in March), 348.5 (elevated, in July) TREATMENT AND OUTCOMES: She was not placed on a return to running program due to underlying metabolic issues. She was referred to Endocrinology, who ordered the 24 hour urine collections, and then referred to GI, who prescribed Linzess. Endocrinology recommended a low salt diet and Vitamin D supplementation. Cholecystectomy can reduce absorption of Vitamin D leading to decreased calcium absorption. She was advised to take a thiazide diuretic to increase her serum calcium levels.