24 hour fasting and measurement of insulin/C-peptide
- if non-diagnostic, a 48-72 fasting may be attempted
Additional provocative tests:
-Stimulation with tolbutamide or calcium infusion resulting in rapid increase in circulating insulin levels
LOCATING THE TUMOR:
Abdominal CT, ultrasound of the pancreas, MRI, or nuclear medicine scanning with radiolabelled somatostatin analougue.
Note that among gut neuroendocrine tumors, somatostatin imaging is least successful in patients with insulinomas.
Angiography with the simultaneous infusion of calcium produces positive results in about 85% of patients.
Portal vanous sampling could locate these tumors (75-100%) but difficult to do!
Endoscopic or intraoperative ultrasound may have a higher sensitivity.
1. Surgical resection of tumor (usually solitary). Presence of MEN-1 does not preclude surgical resection.
2. Octreotide - may reduce insulin release
3. Diazoxide - an antihypertensive agent that can suppress insulin release in 50% of patients
4. Chemotherapy -
Mild diabetes or glucose intolerance
migratory necrolytic erythema (when metastasized)
Hypercoagulable state in up to 1/3rd of patients
Weight loss, mucositis, neuropsychiatric manifestations
2. Glucagon levels above 1000 pg/ml in conjunction with the syndrome. Lesser levels may be noted in other conditions such as renal failure, live disease, or stress.
1. Surgery (hope for cure)
3. IFN + 5FU (helpful for rash, glucagon levels, & tumor size)
Profuse watery diarrhea, hypokalemia, achlorhydra
Stool volumes can exceed 700 ml/d & 70% of patients excrete more than 3 liter/d!
Less Common- abdominal cramping, flushing, hypercalcemia, hypophosphatemia
Elevated circulating VIP> 60 pmole/liter
CT will localize up to 70% of them
Up to 75% are in the pancreas. Other areas include: the lung, colon, or liver.
Note that about 50% of these tumors have metastasized at the time of diagnosis
1. Control the diarrhea!
2. Surgical resection of the tumor
Diabetes (inhibiting insulin secretion)
Steatorrhea (inhibiting gallbladder contraction)
Note that up to 50% of patients with carcinoid tumors are asymptomatic!
-respiratory tree, pancreas, stomach, proximal duodenum
-can produce a number of hormones: 5-HIAA, serotonin, histamine, adrenocorticotropic hormone
-can cause flushing (less common than midgut tumors)
-duodenum, jejunum, ilieum,appendix, R-colon
-can produce serotonin
-cause the most common symptoms of carcinoid (flushing, diarrhea, asthma, heart valve disease, facial telangiectasia)
-L-colon & rectum
-produce serotonin & sometimes catecholamines & other neuropeptides.
1. Urinary 5-HIAA
-note that many foods are rich in serotonin such as nuts, bananas, walnuts, pineapples, pecans. Also, drugs such as tylenol can increase 5-HIAA.
2. Platelet Serotonin level
-measurement not affected by the ingestion of serotonin-rich food.
-useful for foregut tumors because U. or serum 5-HIAA not useful.
3. Provocative testing with pentagastrin infusion
-Releases serotonin in 75% & cause flushing in almost 100% of patients.
(for those who are candidates for chemotherapy)
5FU + Streptozocin
Doxorubicin + Sterptozocin
-studies have indicated that this is superior to 5FU+streptozocin. Dox containing regimen produce an almost 70% objective remission rate and a significantly increased median surival.
Cisplatin + Etoposide
-This is a choice in poorly differentiated neuroendcrine tumors of the gut. You can use any chemotherapy that works with small cell carcinoma of the lung.