```html

Zollinger‑Ellison Syndrome‑Related Hypercalcemia

Overview

Zollinger‑Ellison syndrome (ZES) is a rare endocrine disorder in which one or more gastrin‑producing tumors (gastrinomas) develop in the pancreas or duodenum. The excess gastrin stimulates the stomach to secrete large amounts of gastric acid, leading to severe peptic ulcer disease. Approximately 1‑3 people per million develop ZES each year, making it an orphan disease.

In up to 30 % of patients with ZES, the gastrinoma is part of the multiple endocrine neoplasia type 1 (MEN‑1) syndrome. MEN‑1 also predisposes patients to hyperparathyroidism, which raises blood calcium levels (hypercalcemia). When hypercalcemia co‑exists with ZES, the two conditions can worsen each other: high calcium stimulates gastrin release, while massive gastrin secretion can aggravate calcium loss from bone.

Although ZES can affect individuals of any age, it most commonly presents in the 4th‑5th decade of life and is slightly more prevalent in men (≈55 %). Hypercalcemia in this setting is usually mild‑to‑moderate (serum calcium 10.5‑13 mg/dL) but can become severe (>14 mg/dL) if the underlying parathyroid disease is aggressive.

Symptoms

Symptoms result from two overlapping processes: excess gastric acid and elevated calcium. The list below groups them for clarity.

Symptoms related to excess gastric acid (ZES)

• Recurrent peptic ulcers – often multiple, >3 cm, or located beyond the duodenum (jejunum, ileum).
• Abdominal pain – burning or gnawing pain that may improve with food.
• Diarrhea – secretory diarrhea caused by acid‑induced fluid loss.
• Heartburn/GERD – acid reflux that is refractory to standard therapy.
• Nausea & vomiting – especially after meals.
• Weight loss – due to malabsorption and chronic diarrhea.

Symptoms of hypercalcemia

• Polyuria and polydipsia – kidneys excrete excess calcium, leading to dehydration.
• Fatigue & weakness – calcium interferes with neuromuscular function.
• Bone pain or fractures – due to increased bone resorption.
• Constipation – slowed gut motility.
• Neuropsychiatric changes – confusion, depression, or irritability.
• Cardiac arrhythmias – shortened QT interval, especially in severe cases.
• Kidney stones – calcium oxalate stones are common.
• Pancreatitis – hypercalcemia can precipitate pancreatitis, which may further complicate ZES.

Causes and Risk Factors

Hypercalcemia in ZES is usually secondary to a coexisting endocrine disorder rather than the gastrinoma itself.

Primary Causes

1. MEN‑1 syndrome – a germline mutation in the MEN1 gene leads to tumors of the parathyroid glands (primary hyperparathyroidism) in ~75 % of affected individuals.<sup>1</sup>
2. Secondary hyperparathyroidism from vitamin D deficiency or chronic kidney disease – less common but can coexist.
3. Ectopic production of parathyroid‑related hormone by gastrinomas – rare case reports describe gastrinomas that secrete PTH‑related peptide.

Risk Factors

• Family history of MEN‑1 or other endocrine neoplasias.
• Personal history of pancreatic or duodenal neuroendocrine tumors.
• Radiation exposure to the abdomen (increases risk of neuroendocrine tumors).
• Long‑standing chronic kidney disease (CKD) – predisposes to secondary hyperparathyroidism.
• Excessive calcium or vitamin D supplementation (should be avoided in known hyperparathyroidism).

Diagnosis

Because the two conditions influence each other, a stepwise approach is recommended.

Laboratory Tests

• Serum gastrin level – fasting levels > 1,000 pg/mL are highly suggestive of ZES.<sup>2</sup>
• Secretin stimulation test – gastrin rises > 120 pg/mL after IV secretin in ZES.
• Serum calcium and ionized calcium – total calcium > 10.5 mg/dL or ionized calcium > 1.32 mmol/L signals hypercalcemia.
• Parathyroid hormone (PTH) level – elevated or inappropriately normal PTH confirms primary hyperparathyroidism.
• 24‑hour urinary calcium – helps differentiate hyperparathyroidism from other causes.
• Renal function panel, vitamin D (25‑OH), and magnesium – assess contributors and complications.

Imaging Studies

• Endoscopic ultrasound (EUS) – highly sensitive for locating gastrinomas (<90 %).
• Multiphasic contrast CT or MRI of the abdomen – evaluates tumor size, metastasis, and parathyroid adenomas.
• Somatostatin receptor scintigraphy (Octreoscan) or ^68Ga‑DOTATATE PET/CT – detects neuroendocrine tumor spread.
• Sestamibi scan – localizes hyperfunctioning parathyroid tissue.

Diagnostic Criteria for ZES‑Related Hypercalcemia

1. Fasting serum gastrin > 1,000 pg/mL (or positive secretin test) AND
2. Hypercalcemia (total calcium > 10.5 mg/dL) AND
3. Elevated or inappropriately normal PTH level, confirming primary hyperparathyroidism.

Treatment Options

Management must address both the gastrinoma and the hyperparathyroidism. A multidisciplinary team (gastroenterology, endocrinology, surgery, nutrition) provides the best outcomes.

Medical Therapy for Gastrinoma

• Proton pump inhibitors (PPIs) – high‑dose omeprazole 40‑80 mg daily or equivalent; they control acid hypersecretion in > 90 % of patients.<sup>3</sup>
• H2‑receptor antagonists – added in refractory cases.
• Somatostatin analogs (octreotide, lanreotide) – reduce gastrin secretion and may shrink tumor size.

Surgical Management of Gastrinoma

• Enucleation or segmental resection for isolated, non‑metastatic tumors.
• Pancreaticoduodenectomy (Whipple procedure) for larger or multiple lesions, especially when malignancy is suspected.
• Curative surgery offers the only chance for long‑term remission; 5‑year survival exceeds 80 % when tumors are resected early.<sup>4</sup>

Treatment of Hyperparathyroidism (Hypercalcemia)

• Hydration with isotonic saline – first‑line for symptomatic hypercalcemia; promotes renal calcium excretion.
• Loop diuretics (e.g., furosemide) – used after adequate hydration to increase calcium loss.
• Calcitonin – rapid but short‑acting (effects within 4‑6 h).
• Bisphosphonates (zoledronic acid, pamidronate) – inhibit bone resorption; useful for severe or persistent hypercalcemia.
• Cinacalcet – a calcimimetic that lowers PTH and serum calcium; indicated in MEN‑1 patients who are not surgical candidates.
• Parathyroidectomy – definitive treatment for primary hyperparathyroidism; minimally invasive focused exploration is now standard.

Lifestyle & Supportive Measures

• Limit calcium‑rich foods (dairy, fortified juices) only if directed by your doctor.
• Avoid high‑dose vitamin D supplements unless deficiency is proven.
• Stay well‑hydrated (aim for > 2 L fluid intake daily, unless contraindicated).
• Quit smoking and limit alcohol – both worsen ulcer disease.

Living with Zollinger‑Ellison Syndrome‑Related Hypercalcemia

Adapting daily life can reduce symptom burden and improve quality of life.

Medication Adherence

• Take PPIs exactly as prescribed—missing doses can trigger ulcer bleeding.
• If you have a bisphosphonate, remain upright for 30 minutes after taking it to avoid esophageal irritation.

Nutrition

• Small, frequent meals – reduces acid load and eases diarrhea.
• Choose low‑fat, low‑acid foods (e.g., oatmeal, bananas, boiled potatoes).
• Include calcium‑rich foods only if your calcium level is < 10.5 mg/dL and your physician approves.
• Maintain a balanced intake of vitamin D (800‑1,000 IU/day) unless hypercalcemia is severe.

Monitoring

• Serum calcium, PTH, and gastrin should be checked every 3–6 months after diagnosis, then annually if stable.
• Endoscopic surveillance every 1‑2 years to detect new ulcers or tumor recurrence.
• Bone mineral density (DEXA) every 2 years if hyperparathyroidism persists.

Psychosocial Support

• Join support groups for neuroendocrine tumors or MEN‑1 (e.g., MEN1.org).
• Consider counseling to cope with chronic disease anxiety.

Prevention

Because the underlying gastrinomas are largely sporadic, true primary prevention is limited. However, risk can be mitigated:

• Genetic counseling for families with known MEN‑1 mutations; early screening can detect parathyroid disease before severe hypercalcemia develops.
• Regular medical check‑ups for individuals with known endocrine neoplasia—annual calcium, PTH, and gastrin panels.
• Avoid excessive calcium/vitamin D supplementation unless medically indicated.
• Maintain a healthy lifestyle—balanced diet, regular exercise, and avoidance of smoking reduce ulcer complications.

Complications

If left untreated, the combined effect of uncontrolled acid secretion and hypercalcemia can lead to serious, sometimes life‑threatening problems.

• Peptic ulcer perforation – can cause peritonitis and sepsis.
• Gastrointestinal bleeding – often massive, requiring transfusion or endoscopic therapy.
• Pancreatitis – hypercalcemia precipitates enzyme activation.
• Nephrolithiasis and chronic kidney disease – recurrent stones and calcium deposition impair renal function.
• Osteoporosis or pathological fractures – due to chronic bone resorption.
• Cardiac arrhythmias – especially in severe hypercalcemia (> 14 mg/dL).
• Metastatic gastrinoma – about 25 % of sporadic gastrinomas develop metastases, most commonly to the liver.

When to Seek Emergency Care

---

References

1. J. G. Cushing et al., “MEN1 and associated endocrine tumors,” Endocrine Reviews, 2020.
2. Cleveland Clinic, “Zollinger‑Ellison Syndrome,” accessed May 2026, link.
3. Mayo Clinic, “Zollinger‑Ellison syndrome treatment,” 2023, link.
4. A. C. Strosberg et al., “Surgical outcomes for gastrinomas,” JAMA Surgery, 2019.
5. National Institutes of Health, “Hyperparathyroidism,” 2022, link.
6. World Health Organization, “Rare diseases: definition and registration,” 2021.

```