Theophylline as a Treatment for Children With Pseudohypoparathyroidism Type 1a (Albright Hereditary Osteodystrophy)

Inclusion Criteria: 1. Age 10 to 21 years old 2. English proficiency 3. Clinical and genetic diagnosis of PHP1a Exclusion Criteria: 1. Use of a PDE inhibitor in the past 30 days 2. History of a seizure disorder unrelated to hypocalcemia 3. History of a cardiac arrhythmia (not including bradycardia) 4. History of hepatic insufficiency 5. AST or ALT \>2x upper limit of normal 6. Total bilirubin \>1.5 x upper limit of normal (unless patient has a diagnosis of Gilbert's syndrome and no other causes leading to hyperbilirubinemia are identified) 7. Congestive heart failure 8. Cigarette use in the past 30 days 9. Alcohol use within the past 24 hours 10. Current pregnancy 11. Untreated hypothyroidism (defined as free T4 level \< 0.6 ng/dL or TSH \>10 mcU/mL) 12. Active peptic ulcer disease 13. Fever \>101 degrees in the past 24 hours 14. Current use of medications known to effect theophylline levels (listed below) 15. Severe sleep apnea requiring BiPAP Drugs with clinically significant drug interactions with theophylline: * Allopurinol * Cimetidine * Ciprofloxacin * Clarithromycin * Enoxacin * Ephedrine * Erythromycin * Estrogen * Flurazepam * Fluvoxamine * Lithium * Lorazepam * Methotrexate * Midazolam * Pentoxifylline * Propranolol * Rifampin * Sulfinpyrazone * Tacrine * Thiabendazole * Ticlopidine * Troleandomycin * Verapamil