A 19 year-old female is referred following a visit to the dentist where marked erosion of her teeth was noted. She was entirely asymptomatic and her only medication was the oral contraceptive pill. On examination her blood pressure was 110/70 mmHg and her body mass index was 21.5 kg/m2 (18 - 25). Investigations sodium 135 mmol/l potassium 2.1 mmol/l bicarbonate 42 mmol/l urea 2.6 mol/L corrected calcium 2.08 mmol/ alkaline phosphatase 201 iu/l (50-110) What is the most likely diagnosis? 1) Bulimia nervosa 2) Conn's syndrome 3) Laxative abuse 4) Pregnancy 5) Primary hypoparathyroidism