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25 N Winfield Rd Ste 505, Winfield, IL 60190-1295

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Call
(630) 938-6161
to Schedule a Consultation

25 N Winfield Rd Ste 505
Winfield IL 60190-1295

Primary Hyperparthyroidism

Diagnosis

Primary Hyperparthyroidism Diagnosis

Diagnosis of Primary Hyperparathyroidism (pHPT).

Blood tests showing elevated calcium and PTH levels at the same time.

  • Calcium and PTH levels can fluctuate in pHPT, therefore multiple (minimum 3) blood tests over time are needed.

24-hour urine collection showing normal to elevated calcium levels.

  • Not always essential for diagnosis, but helpful when considering normocalcemic variant of pHPT (to rule out FHH – see ‘Variants’ section in the left topics column).

This is a biochemical diagnosis – made by blood and urine laboratory results alone.

  • Imaging tests showing a parathyroid adenoma is NOT NECESSARY to make the diagnosis of pHPT.
    • Localizing imaging tests are only helpful for surgical planning once the diagnosis has ALREADY been made.
    • Not used to confirm or exclude the diagnosis of pHPT.

Additional Work-up:

  • DEXA – Dual-energy x-ray absorptiometry.
  • Abdominal imaging to rule out asymptomatic kidney stones (silent nephrolithiasis) or nephrocalcinosis (calcification of the kidney).
    • Both are not necessary for making a diagnosis, but helpful in decision making for treatment.

Variants of pHPT – can be more challenging to diagnose.

Normo-hormonal pHPT

  • High calcium levels with high normal (non-suppressed) or fluctuating elevated PTH levels.
    • Loss of ‘teeter totter’ effect – if calcium levels are elevated and the parathyroid glands are working appropriately, the PTH levels should be suppressed – very low or low normal.
      • If you are given very high doses of calcium in your diet or through an IV, and you have normal parathyroid gland function, your PTH levels will be suppressed (drop very low).
    • If PTH levels are normal or high normal (non-suppressed or inappropriately normal) when calcium levels are elevated, then the parathyroid gland(s) have dysfunction and the diagnosis of pHPT is made.
  • At least 3 blood tests over time are needed to ensure this diagnosis.
    • Consider additional tests to rule out other causes for elevated calcium levels (especially if PTH levels are low).
      • PTHrp (PTH related protein), Vit D 1,25, Alkaline Phosphatase (ALP), ACE level, SPEP / UPEP, TSH.
      • Read more with Hypercalcemia Overview.
    • Discontinue any medications that can cause elevated calcium levels:
      • Calcium supplements, thiazide diuretics (eg hydrochlorothiazide), lithium, excess Vit D, Tamoxifen.

Normo-calcemic pHPT

  • High normal or fluctuating elevated calcium levels, elevated PTH levels.
  • At least 3 blood tests over time are needed to ensure this diagnosis.
    • Ionized calcium and albumin corrected calculations of calcium (more accurate measurement of calcium in the blood, dependent on pH and protein levels) can be helpful in considering this diagnosis.
    • Rule out causes for Secondary Hyperparathyroidism (sHPT) and correct if possible.
      • Ensure Vit D levels are normal.
        • Common in regions with less sun exposure and low dairy diets.
      • Rule out kidney dysfunction (blood creatinine and GFR) and renal calcium leak.
      • Rule out malabsorption of calcium.
        • Gastric bypass / bariatric surgery, Celiac disease.
          • Start calcium citrate.
    • Rule out Familial Hypocalciuric Hypercalcemic (FHH – see below)
      • 24-hour urine collection measuring calcium and creatinine.
        Consider if 24-hour urine calcium is < 100 or if fractional excretion of calcium (FeCa) is < 0.01.

      • Typically, a family history is present.
        • Red flag if previous family members had parathyroidectomy without a cure.
    • Consider stopping medications that can cause low blood calcium.
      • Bisphosphonates (eg Fosamax), Prolia (Denosumab), Cinacalcet (Sensipar), Dilantin (Phenytoin), Loop Diuretics (eg furosemide), PPI (eg omeprazole).
  • More common to present with multi-gland disease (double adenoma or 4 gland hyperplasia).
    • Imaging studies are often non-localizing due to smaller adenomas / hyperplasia glands.
      • Positive imaging is NOT necessary to make a diagnosis; meant to help in surgical planning.
      • Negative imaging DOES NOT rule out pHPT.
  • These variants are NOT considered to be less symptomatic than classic pHPT.

Inherited autosomal dominant disease (only one parent needs to have this to pass it on to a child).

  • Mutation in calcium sensing receptor (CASR) protein.
    • Parathyroid glands and kidneys are less sensitive to serum calcium levels, causing inappropriate PTH production and renal calcium reabsorption.
  • Very rare, prevalence ~ 1:100,000 people.
  • Patients are mainly asymptomatic.

Diagnosis:

  • Calcium is high end of normal or mildly elevated (can fluctuate).
  • PTH normal or mildly elevated (can fluctuate).
    • Differentiate from primary hyperparathyroidism (normo-calcemic variant):
      • Low 24-Hour urine Ca (typically < 100) and fractional excretion of calcium < 0.01.
      • Can confirm with mutational analysis of the CASR gene (blood draw).

To be considered in work-up of pHPT, especially normo-calcemic variant.

Treatment is NOT surgical (why it is very important to distinguish from pHPT).

  • There are no ‘end organ’ effects as there are with pHPT (bone, blood vessels, kidneys, etc.).
  • Medical treatment with dietary changes / close observation.

Increased suspicion for FHH if + family history of hypercalcemia not cured by parathyroidectomy.

To learn more about Parathyroid:

 

Return to the Parathyroid main page here.

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