title: Primary hyperparathyroidism as the first clinical manifestation of multiple endocrine neoplasia type 2A in a 5-year-old child.
abstract: BACKGROUND
  Primary hyperparathyroidism occurs in only 10%-30% of patients with multiple endocrine neoplasia type 2A (MEN2A), rarely as the sole clinical manifestation, and is usually diagnosed after the third decade of life.
  
  
  CONCLUSIONS
  A 5-year-old girl was referred for prophylactic thyroidectomy as she carried the p.C634R RET mutation. She was clinically asymptomatic, with a normally palpable thyroid and with the cervical region free of lymphadenopathy or other nodules. Preoperative tests revealed hypercalcemia associated with elevation of parathyroid hormone (PTH) (calcium = 11.2 mg/dL, calcium ion = 1.48 mmol/L, phosphorus = 4.0 mg/dL, alkaline phosphatase = 625 U/L, parathyroid hormone (PTH) PTH = 998 pg/mL). A thyroid ultrasound was normal and parathyroid scintigraphy with (99m)Tc-Sestamibi revealed an area of radioconcentration in the upper half of the left thyroid lobe suggesting hyperfunctioning parathyroid tissue. She underwent total thyroidectomy and parathyroidectomy and developed hypocalcemia. The anatomopathological examination showed no histopathological changes in the thyroid tissue and an adenoma of the parathyroid gland, confirming the diagnosis of hyperparathyroidism.
  
  
  CONCLUSIONS
  Primary hyperparathyroidism can be a precocious manifestation of MEN2A. This case report highlights that asymptomatic hypercalcemia should be scrutinized in children related to patients with MEN2A who carry a mutation in the RET proto-oncogene, especially mutations in the codon 634, before the currently recommended age of 8 years.
authors: Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Sao Paulo, Ribeirao Preto, Brazil.
authors: Patrícia Künzle Ribeiro
authors: PK
authors: Magalhães
authors: Sonir Roberto Rauber
authors: SR
authors: Antonini
authors: Francisco José Albuquerque
authors: FJ
authors: de Paula
authors: Luiz Carlos Conti
authors: LC
authors: de Freitas
authors: Léa Maria Zanini
authors: LM
authors: Maciel
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D002118:Calcium / Q000737:chemistry; D002675:Child, Preschool; D003062:Codon; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000097:blood / Q000235:genetics; D006961:Hyperparathyroidism / Q000150:complications / Q000175:diagnosis*; D018813:Multiple Endocrine Neoplasia Type 2a / Q000150:complications / Q000175:diagnosis*; D009154:Mutation; D010281:Parathyroid Hormone / Q000097:blood; D010758:Phosphorus / Q000378:metabolism; D000090063:Proto-Oncogene Mas; D051096:Proto-Oncogene Proteins c-ret / Q000235:genetics; D013667:Technetium / Q000378:metabolism
chemical_list: D003062:Codon; C000715470:MAS1 protein, human; D010281:Parathyroid Hormone; D000090063:Proto-Oncogene Mas; D010758:Phosphorus; D013667:Technetium; D051096:Proto-Oncogene Proteins c-ret; C099282:RET protein, human; D000469:Alkaline Phosphatase; D002118:Calcium