Calcium disorders and parathyroid surgery
Stem
A 63-year-old woman, 72 kg, with primary hyperparathyroidism from a single adenoma is admitted confused and dehydrated, with a total calcium of 13.8 mg/dL, ionized calcium 1.82 mmol/L, creatinine 1.6 (baseline 0.9), and an alkaline phosphatase three times normal. Her ECG shows a short QT interval. The endocrine surgeon wants to do a focused parathyroidectomy in 48 hours, and imaging shows osteopenia with a recent vertebral compression fracture.
Question
How will you get her ready for surgery, and what will you watch for afterward?
Ideal answer
HeadlineSevere symptomatic hypercalcemia with acute kidney injury: I restore her volume and bring the calcium down before anesthesia.
- Balanced crystalloid to euvolemia, then urine-guided maintenance. She is dry; no forced diuresis with furosemide, which has not been shown to help.1
- Calcitonin 4 units/kg subcutaneously every 12 hours. About 290 units; it works within hours but stops after about two days, so it bridges to a bisphosphonate.1
- Zoledronic acid 4 mg now. Over at least 15 minutes, no renal reduction for hypercalcemia, avoided in severe renal impairment; slow to act.2
- Ionized calcium and ECG; careful positioning. Ionized, not a corrected total;1 fragile bones; intraoperative PTH and any nerve monitoring agreed with the surgeon.
- Afterward: hematoma, recurrent laryngeal nerve, then hypocalcemia. Raised alkaline phosphatase and bone disease put her at risk of hungry bone syndrome;3 calcium, magnesium and phosphate checked regularly.
Breaking down the answer
- Why she is dry — the polyuria of hypercalcemia makes her hypovolemic, so rehydration is itself the first treatment; forced diuresis adds risk without benefit.1
- Match drug to timeline — denosumab is an option when renal failure limits bisphosphonates;1 with surgery in 48 hours, the fast-but-transient and the slow-but-lasting drugs both matter.1
- Read the ECG — a short QT may be the most common and useful ECG finding; extreme levels cause AV block and bradyasystolic arrest.1
- Trust ionized calcium — albumin-corrected formulas perform worse than uncorrected values.1
- Predict hungry bone syndrome — risk factors are a high PTH and alkaline phosphatase, radiological bone disease, larger glands and, in primary disease, older age and a higher preoperative calcium.3 She has several, so I plan the monitoring before surgery.
- Know the incidence — historically about 13% after surgery for primary hyperparathyroidism, and 20 to 70% after surgery for secondary disease.3
Follow-up question
On the second postoperative day she reports perioral numbness and hand cramps, then develops inspiratory stridor. Her total calcium is 6.9 mg/dL and the QTc is 520 ms. The wound looks flat. What do you do?
Follow-up answer
HeadlineSymptomatic hypocalcemia with laryngospasm, most likely the start of hungry bone syndrome; I call for help, tell the surgeon and support the airway.
Bilateral nerve injury and hematoma stay on the differential; a flat wound makes a hematoma less likely. Oxygen, ready to intubate. I give 10 to 20 mL of 10% calcium gluconate in 50 to 100 mL of D5W over 5 to 10 minutes, then 0.5 to 1.5 mg/kg/h of elemental calcium, 36 to 108 mg/h for her.3 I replace magnesium, because hypomagnesemia blocks calcium correction, and start calcitriol 0.25 to 1 mcg a day with oral calcium.3 Calcium, phosphate and magnesium every 4 to 6 hours, and a repeat ECG.3
Pitfalls that cost points
- Assuming the danger is over once PTH falls in theater.
- Calling postoperative stridor a hematoma without checking calcium.
Rapid-fire
Q: When does hypocalcemia need IV calcium? A: Calcium below 7.6 mg/dL, symptoms, or ECG changes such as QTc prolongation.3
Q: Why replace magnesium? A: Persistent hypomagnesemia impairs PTH action and blunts calcium replacement.3
Q: When is dialysis used for hypercalcemia? A: In severe renal failure, for example GFR below 10 to 20 mL/min, though the effect may be transient.1
Q: What are the signs of hypocalcemia after neck surgery? A: Perioral and acral tingling, carpopedal spasm, tetany, seizures, laryngospasm and arrhythmias.3
Numbers to know
| Item | Value |
|---|---|
| Calcitonin | 4 units/kg SC every 12 h; fades after ~2 days1 |
| Zoledronic acid | 4 mg IV over ≥15 min; no renal reduction for hypercalcemia; avoid in severe renal impairment2 |
| Hungry bone definition | Calcium <8.4 mg/dL beyond day 43 |
| Calcium gluconate bolus | 10–20 mL of 10% over 5–10 min3 |
| Calcium infusion | 0.5–1.5 mg/kg/h elemental3 |
| Calcitriol | 0.25–1 mcg/day3 |
Links
- Thyroid disease, thyroid storm and thyroidectomy, Chronic kidney disease and the dialysis patient, Fluid management: crystalloid, colloid, goal-directed, laryngospasm, Acute kidney injury
- IBCC hypercalcemia chapter
Sources
- 1.Hypercalcemia (Internet Book of Critical Care) · EMCrit / IBCC (Farkas), 2023 · emcrit.org
- 2.Zoledronic acid injection 4 mg/5 mL prescribing information · FDA / DailyMed (Hikma) · dailymed.nlm.nih.govHypercalcemia of malignancy: 4 mg over no less than 15 minutes; no dose adjustment for serum creatinine below 4.5 mg/dL; severe renal impairment only after weighing risks and benefits.
- 3.Hungry Bone Syndrome · StatPearls, 2025 · dev3.statpearls.comNo consensus definition; most sources use calcium <8.4 mg/dL persisting beyond postoperative day 4.
Facts on this page were checked against these sources on Oct 16, 2026. Guidelines change; confirm doses against current institutional protocols.