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(70 %), and gastric neuroendocrine tumors (10 %). Rarely, pheochromocytoma
(<1 %) and thymic NET (<2 %) have also been described.- Who should be screened for MEN1?
Screening for MEN1 should be performed in a patient with ≥2 MEN1-
associated endocrine tumors (parathyroid, pancreatic, and pituitary tumor),
asymptomatic first-degree relatives of an individual with MEN1 mutation, or
patients who have ≥2 MEN1-associated endocrine tumors that are not part of
classical triad of parathyroid, pancreatic, or pituitary tumor (e.g., pancreatic
and adrenal). In addition, patients with PHPT <30 years of age, multiglandular
parathyroid disease, gastrinoma, and multiple pancreatic neuroendocrine tumor
should also be screened for MEN1 syndrome.- When to suspect MEN1 syndrome in a patient who presents with single endo-
crine gland involvement?
Primary hyperparathyroidism (PHPT) is the most common and the earliest
manifestation of MEN1 syndrome. Therefore, PHPT in a young individual
(<30 years) or multiglandular parathyroid involvement should raise a suspicion
of MEN1 syndrome. In addition, patients with acid peptic disease who have
multiple ulcerations at unusual sites (second part of the duodenum and jeju-
num), resistance to proton pump inhibitor therapy, or recurrence of peptic ulcer
disease after surgery should raise a suspicion of gastrinoma. The probability of
having MEN1 syndrome in a patient with gastrinoma is approximately 25 %,
and hence, every patient with gastrinoma should be evaluated for MEN1 syn-
drome. In addition, patients with multiple pancreatic NET at any age should
also be evaluated for MEN1 syndrome. Pituitary tumor occurs in 15–50 % of
patients with MEN1 syndrome and can manifest as early as 5 years of age or as
late as in ninth decade with a mean age of 38 years. On the contrary <3 % of
patients with pituitary tumor have MEN1. Therefore, screening for MEN1 in a
patient with isolated pituitary tumor is not rewarding.- A 21-year-old man presented with pathological fracture of shaft of the femur.
His biochemical profile showed corrected serum calcium 11.5 mg/dl, phos-
phate 2.1 mg/dl, alkaline phosphatase 315 IU/L, iPTH 300 pg/ml, and 25(OH)D
20 ng/ml. Ultrasonography showed left and right inferior parathyroid ade-
noma. His family history was noncontributory. How to approach further?
The clinical and biochemical profile of the index patient suggest the diagnosis
of primary hyperparathyroidism (PHPT). Young age of onset and the presence
of multiglandular disease in a patient with PHPT mandate screening for MEN1
syndrome. The investigations required for the detection of other endocrine
organ involvement include estimation of serum gastrin, fasting plasma glucose,
insulin and C-peptide, prolactin, and chromogranin A. However, it should be
further corroborated with genetic analysis for MEN1 gene mutation. Preoperative11 Multiple Endocrine Neoplasia