What does an elevated parathyroid hormone level of 204 pg/mL indicate and how should it be evaluated and treated?

Elevated PTH of 204 pg/mL: Evaluation and Management

A PTH level of 204 pg/mL requires immediate assessment of serum calcium, kidney function, and vitamin D status to distinguish between primary hyperparathyroidism (which requires surgical evaluation), secondary hyperparathyroidism (which requires medical management), or tertiary hyperparathyroidism (which may require surgery). 1, 2

Initial Diagnostic Workup

Measure these laboratory values simultaneously:

• Serum calcium (corrected for albumin) – If elevated or high-normal with PTH 204, this confirms primary hyperparathyroidism 2, 3
• Serum creatinine and eGFR – PTH increases with declining kidney function; eGFR <60 mL/min/1.73 m² suggests secondary hyperparathyroidism from chronic kidney disease 1
• 25-hydroxyvitamin D level – Vitamin D deficiency is the most common cause of secondary hyperparathyroidism and must be excluded; levels should be >20 ng/mL (>50 nmol/L) 3, 4
• Serum phosphate – Low-normal phosphate supports primary hyperparathyroidism, while elevated phosphate suggests CKD-related secondary hyperparathyroidism 1, 5
• 24-hour urine calcium or spot urine calcium/creatinine ratio – To assess calcium excretion and rule out familial hypocalciuric hypercalcemia 3, 6

Interpretation Based on Calcium and Kidney Function

If Calcium is Elevated (>10.2 mg/dL) with Normal Kidney Function

This is primary hyperparathyroidism requiring surgical evaluation. 2, 3

• PTH of 204 pg/mL is inappropriately elevated in the setting of hypercalcemia (PTH should be suppressed) 5, 7
• Refer immediately to endocrinology and an experienced parathyroid surgeon for evaluation of parathyroidectomy 2, 5
• Absolute surgical indications include: corrected calcium >1 mg/dL above upper limit of normal, age <50 years, eGFR <60 mL/min/1.73 m², osteoporosis (T-score ≤-2.5), nephrolithiasis, or hypercalciuria (>300 mg/24hr) 2, 5
• Obtain preoperative localization imaging with neck ultrasound and/or 99mTc-sestamibi scan with SPECT/CT once diagnosis is biochemically confirmed 2, 5

If Calcium is Normal with Normal Kidney Function

This is either normocalcemic primary hyperparathyroidism or secondary hyperparathyroidism. 3, 4

First, exclude all secondary causes before diagnosing normocalcemic primary hyperparathyroidism:

• Vitamin D deficiency – Supplement if 25-hydroxyvitamin D <20 ng/mL with cholecalciferol 1000-2000 IU daily, then recheck PTH after 3 months of vitamin D repletion 3, 4
• Inadequate dietary calcium intake – Confirm intake of 1000-1200 mg/day; low calcium intake causes compensatory PTH elevation 3, 4
• Medications – Review for thiazide diuretics, lithium, or biotin supplements that can elevate PTH 1, 4
• Malabsorption disorders – Celiac disease, inflammatory bowel disease, or post-bariatric surgery can impair calcium absorption 4, 8

If all secondary causes are excluded and PTH remains elevated with persistently normal calcium:

• This is normocalcemic primary hyperparathyroidism, which carries similar risks to hypercalcemic disease including bone loss and kidney stones 3, 4
• Refer to endocrinology for evaluation; surgical candidacy depends on presence of complications (osteoporosis, nephrolithiasis, progressive bone loss) 3, 4

If Kidney Function is Impaired (eGFR <60 mL/min/1.73 m²)

Determine whether this is secondary or tertiary hyperparathyroidism based on calcium levels. 1, 9

For CKD Stage 3 (eGFR 30-59 mL/min/1.73 m²) with PTH 204 pg/mL:

• If calcium is normal or low, this is secondary hyperparathyroidism requiring medical management 1, 8
• Target PTH levels: 2-9 times the upper normal limit of the assay (approximately 70-110 pg/mL for Stage 3) 1
• Initial management: Dietary phosphate restriction, phosphate binders (non-calcium-based preferred if calcium >10.2 mg/dL), correct vitamin D deficiency, and ensure adequate calcium intake 1, 2
• If PTH remains >110 pg/mL despite these measures, consider calcitriol or vitamin D analogs (doxercalciferol, paricalcitol) 1, 2

For CKD Stage 4-5 (eGFR <30 mL/min/1.73 m²) with PTH 204 pg/mL:

• Target PTH levels: 2-9 times upper normal limit (approximately 150-300 pg/mL for dialysis patients) 1, 2
• PTH of 204 pg/mL may be appropriate for this stage; treatment depends on calcium and phosphate levels 1
• If calcium is elevated (tertiary hyperparathyroidism), consider parathyroidectomy if refractory to medical management 2, 9

For dialysis patients with PTH >300 pg/mL and hypercalcemia refractory to medical therapy:

• Parathyroidectomy is indicated for persistent PTH >800 pg/mL with hypercalcemia/hyperphosphatemia despite maximal medical therapy 2, 9
• Total parathyroidectomy has lower recurrence rates but higher risk of permanent hypoparathyroidism compared to subtotal parathyroidectomy 2, 9

Critical Pitfalls to Avoid

Do not order parathyroid imaging before confirming biochemical diagnosis – Imaging is for surgical planning only, not diagnosis 3

Do not supplement with vitamin D if calcium is elevated (>10.2 mg/dL) – This will worsen hypercalcemia; discontinue all vitamin D therapy immediately 3

Do not assume PTH elevation is benign in CKD – Even with impaired kidney function, if calcium is elevated, this is tertiary hyperparathyroidism requiring surgical evaluation 5, 9

PTH assays vary by up to 47% between different generations and laboratories – Always use assay-specific reference ranges and the same assay for serial monitoring 1, 3

Use EDTA plasma rather than serum for PTH measurement – PTH is more stable in EDTA plasma at 4°C 1, 3

Biological variation of PTH is substantial (20% in healthy individuals) – Serial PTH values must differ by >54% to be clinically significant 3

PTH has a circadian rhythm and varies by sampling site – Central blood has higher PTH than peripheral blood; optimal sampling time is morning fasting 1

Monitoring Strategy

For confirmed primary hyperparathyroidism awaiting surgery:

• Monitor serum calcium every 3 months 3
• Maintain adequate hydration and avoid thiazide diuretics 3
• Ensure normal calcium intake (1000-1200 mg/day); do not restrict or supplement excessively 3, 5

For secondary hyperparathyroidism on medical therapy:

• Monitor calcium and phosphorus every 2 weeks for 1 month after initiating or adjusting vitamin D therapy, then monthly 2
• Monitor PTH monthly for at least 3 months, then every 3 months once target levels achieved 2
• Discontinue vitamin D immediately if calcium exceeds 10.2 mg/dL 3