From the Guidelines
Vasoactive Intestinal Peptide (VIP) secretions are characterized by watery diarrhea, hypokalemia, and achlorhydria (WDHA syndrome).
Key Features of VIPomas
- Diarrhea: large volumes of secretory diarrhea (>1 litre/day)
- Dehydration: due to excessive fluid loss
- Hypokalaemia: low potassium levels
- Achlorhydria: absence of hydrochloric acid in the stomach
Diagnosis of VIPomas
- Elevated serum VIP concentration: mean VIP serum concentrations in patients with functioning tumours range from 675 to 965 pg/mL 1
- Normal values for circulating VIP: less than 170 pg/mL
- Assay should be performed during an episode of diarrhea: as serum levels fluctuate 1
Clinical Presentation
- Watery diarrhea: occurring in 100% of cases of VIPoma 1
- Hypokalemia: and achlorhydria are also characteristic features of VIPoma 1
Biochemical Evaluation
- Biochemical evaluation is guided by symptoms: that might indicate excess hormone secretion 1
- Serum chromogranin A: may also be tested as clinically appropriate, as it is elevated in 60% or more of patients with either functioning or nonfunctioning pancreatic endocrine tumors 1
From the Research
Secretions of Vasoactive Intestinal Peptide (VIP)
The secretions of Vasoactive Intestinal Peptide (VIP) have various effects on the body, including:
- Regulation of ion secretion, nutrient absorption, gut motility, glycemic control, carcinogenesis, immune responses, and circadian rhythms 2
- Vasodilation, with VIP being 50-100 times more potent than acetylcholine as a vasodilator 3
- Increase in coronary artery blood flow, decrease in coronary vascular resistance, and regulation of normal coronary vasomotor tone 3
- Positive inotropic effect on cardiac muscle, facilitation of ventricular-vascular coupling, and reduction of mean arterial pressure 3
- Augmentation of developed isometric force and increase in atrial and ventricular contractility 3
- Effect on heart rate, with VIP having a more potent effect on heart rate than norepinephrine 3
- Pleiotropic effects as a neurotransmitter, immune regulator, vasodilator, and secretagogue 4
- Involvement in the control of smooth muscle tone and motility, blood flow, and secretion in the digestive tract, respiratory tract, and urogenital tract 5
- Role in circadian rhythms and melatonin and pituitary hormone secretion in the brain 5
Regulation of VIP Secretion
VIP secretion is stimulated by: