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Medicine

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Endocrine

Question
11 out of 15
 

Weight loss may be seen in all of the following except: (LQ)



A Uremia
B Pheochromocytoma

C Adrenal insufficiency
D Insulinoma

Ans. D

Insulinoma (Ref: Hari 18th ed., Pg-3003)

This pancreatic islet cell tumour is associated with MEN-l, and is usually benign. It presents as fasting hypoglycemia, with Whipple's triad:

1). Symptoms associated with fasting or exercise

2). Recorded hypoglycemia with symptoms

3). Symptoms relieved with glucose.

Note: Weight gain occurs in insulinoma

Screening test: Hypoglycemia + plasma insulin during a long fast

Diagnosis of Insulinoma

1). 72 hours Fasting blood glucose levels:

a. The most reliable test to diagnose insulinoma is a fast up to 72 h with serum glucose, C-peptide, and insulin measurements every 4–8 h.

b. It is thought to be “gold standard” test for insulinoma.Q

2). C peptide levels:

a. Insulin is synthesized as proinsulin, a 21-amino-acid alpha-chain and a 30-amino-acid beta-chain connected by a 33-amino-acid connecting peptide (C peptide).

b. In insulinomas, in addition to elevated plasma insulin levels, elevated plasma proinsulin levels are found and C-peptide levels can be elevated.

3). Insulin / glucose ratio:

a. In 72 hr fasting, about 70–80% of patients will develop hypoglycemia during the first 24 h and 98% by 48 h. In nonobese normal subjects, serum insulin levels should decrease to <43 pmol/L (<6 U/mL) when blood glucose decreases to 2.2 mmol/L (40 mg/dL) and the ratio of insulin to glucose is <0.3 (in mg/dL).

b. In addition to having an insulin level >6 U/mL when blood glucose is <40 mg/Dl an insulin/glucose ratio >0.3, l for the diagnosis of insulinomas.

Treatment:

1). Enucleation of a solitary insulinoma is generally curative.

2). Diazoxide, inhibits insulin secretion

3). Octreotide is a Somatostatin analogue. Octreotide is used to treat hypoglycemia in patients with unresectable tumors

4). Recent Advances: In patients with unresectable tumors; Everolimus, an mTOR (Mammalian target of rapamycin) inhibitor, is promising. (H-18th ed. Pg- 3008)

Important Points: Glucagonoma is characterized by Necrolytic migratory erythema

Endocrine Flashcard List

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