ICD-10-CM > E00-E89 > E20-E35 > E21 E21 Hyperparathyroidism and other disorders of parathyroid gland Non-Billable/Non-Specific Type 1 Excludes adult osteomalacia (M83.-)ectopic hyperparathyroidism (E34.2)hungry bone syndrome (E83.81)infantile and juvenile osteomalacia (E55.0) Type 2 Excludes familial hypocalciuric hypercalcemia (E83.52) Codes E21.0Primary hyperparathyroidismE21.1Secondary hyperparathyroidism, not elsewhere classifiedE21.2Other hyperparathyroidismE21.3Hyperparathyroidism, unspecifiedE21.4Other specified disorders of parathyroid glandE21.5Disorder of parathyroid gland, unspecified