Primary hyperparathyroidism happens when one or more parathyroid glands make too much parathyroid hormone, most often from a single benign adenoma. It is the most common cause of high calcium in outpatients and is often found on routine blood tests before any symptoms appear.
Key symptoms
- Often no symptoms
- Kidney stones and frequent urination
- Bone pain and fractures
- Constipation, nausea and abdominal pain
- Fatigue, low mood and poor concentration
What you find on exam
- Usually normal
- Blood pressure
- Signs of dehydration
- Flank tenderness from stones
- Height loss from spine fractures
Tests
- High calcium, corrected for albumin
- PTH high or inappropriately normal; low phosphate
- 24-hour urine calcium to exclude familial hypocalciuric hypercalcemia; vitamin D; kidney function
- Bone density (DXA) and kidney imaging; sestamibi scan or neck ultrasound before surgery
Treatment basics
- Parathyroidectomy cures it and is advised for symptoms or any surgical criterion
- Criteria: calcium over 1 mg/dL above normal, osteoporosis, stones, eGFR under 60 or age under 50
- Cinacalcet to lower calcium if surgery is not possible
- Bisphosphonate to protect bone
- Good hydration; avoid thiazides and lithium when possible
Red flags
- Calcium over 14 mg/dL or confusion
- Severe dehydration or kidney injury
- Low calcium and tetany after surgery (hungry bone syndrome)
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.