What does a parathyroid hormone (PTH) level of 268 indicate and how is it managed?

Management of PTH Level of 268 pg/mL

A PTH level of 268 pg/mL requires immediate assessment of serum calcium, phosphorus, 25-OH vitamin D, and kidney function to determine whether this represents primary hyperparathyroidism (with hypercalcemia) or secondary hyperparathyroidism (with normal or low calcium). 1

Initial Diagnostic Workup

Check the following labs immediately:

• Serum calcium (corrected for albumin) 1
• Serum phosphorus 1
• 25-OH vitamin D level 1
• Serum creatinine and estimated GFR 2
• Review all medications affecting calcium metabolism 1

The calcium level determines your next steps and fundamentally changes the diagnosis and management approach.

If Hypercalcemia is Present (Primary Hyperparathyroidism)

Hypercalcemia with elevated or inappropriately normal PTH confirms primary hyperparathyroidism and requires surgical referral. 3

Proceed with parathyroid imaging:

• Ultrasound of the neck 2
• Dual-phase 99mTc-sestamibi scintigraphy with SPECT/CT (parathyroid scan) 3
• The combination of these two modalities is highly sensitive for localizing parathyroid adenomas 3

Surgical indications at this PTH level:

• Refer to an experienced endocrine surgeon for parathyroidectomy 3
• This is the only definitive cure for primary hyperparathyroidism 3
• Surgical options include resection of a solitary enlarged gland or total four-gland parathyroidectomy with autotransplantation 3
• Consider transcervical thymectomy during the same procedure due to risk of supernumerary parathyroid glands 3

Important caveat: Even with hypercalcemia, check vitamin D levels—primary hyperparathyroidism can coexist with vitamin D deficiency, which may present with paradoxical hypocalcemia 4

If Calcium is Normal or Low (Secondary Hyperparathyroidism)

Normal or low calcium with PTH of 268 pg/mL indicates secondary hyperparathyroidism, most commonly from vitamin D deficiency or chronic kidney disease. 2

Vitamin D Deficiency Management:

• Supplement with cholecalciferol or ergocalciferol to achieve 25-OH vitamin D levels ≥30 ng/mL 1
• Target minimum vitamin D levels >20 ng/mL (50 mmol/L) 1
• This is the first-line treatment for secondary hyperparathyroidism due to vitamin D deficiency 2

Chronic Kidney Disease Management:

If eGFR is reduced, indicating CKD:

Initial medical therapy:

• Dietary phosphate restriction 1
• Phosphate binders if hyperphosphatemia is present 1, 2
• Low-dose active vitamin D (calcitriol or alfacalcidol) as supplement to nutritional vitamin D 1, 2
• Monitor calcium levels closely when initiating vitamin D therapy 2

PTH of 268 pg/mL in CKD context:

• This level falls in the intermediate range (100-500 pg/mL) where interpretation is challenging 1, 2
• PTH levels in this range have insufficient sensitivity and specificity to reliably predict bone disease 1
• Consider bone biopsy if unexplained hypercalcemia, bone pain, or increased bone alkaline phosphatase develops 1, 2

Escalation to calcimimetics:

• If PTH remains elevated despite optimizing active vitamin D (dose increase) and phosphate treatment (dose reduction), consider cinacalcet 3
• Cinacalcet decreases serum PTH and FGF23 levels while increasing TmP/GFR 3
• Critical warning: Cinacalcet is associated with severe adverse effects including hypocalcemia and increased QT interval—close monitoring is mandatory 3
• Cinacalcet is not licensed for non-dialysis CKD but may be considered with caution 3

Surgical threshold:

• Parathyroidectomy is indicated only if PTH persistently exceeds 800 pg/mL with hypercalcemia and/or hyperphosphatemia refractory to medical therapy 1
• At PTH 268 pg/mL, surgery is not indicated unless tertiary hyperparathyroidism develops (persistent hypercalcemic hyperparathyroidism) 3, 2

Monitoring Protocol

Initial intensive monitoring:

• Check serum calcium and phosphorus monthly for the first 3 months 1
• Measure PTH levels every 3 months for 6 months 1

Long-term monitoring:

• Calcium and phosphorus every 3 months 1
• PTH every 3-6 months 1
• For CKD patients on treatment, monitor calcium, phosphorus, and PTH regularly 2

Critical Pitfalls to Avoid

Do not assume secondary hyperparathyroidism based solely on kidney disease—primary hyperparathyroidism can occur in CKD patients and requires different management 4

Do not delay vitamin D supplementation—this is often the reversible cause and should be addressed immediately 1, 2

Do not rush to surgery at this PTH level—unless there is confirmed primary hyperparathyroidism with clear surgical indications, medical management is appropriate 1

Ensure adequate calcium levels before initiating thyroid hormone replacement if concurrent thyroid disorders are present, as this can precipitate hypocalcemia 2, 5