CaPTHUS Model of Kebebew et al for Evaluating a Patient with Primary Hyperparathyroidism

 

Parameters:

(1) total serum calcium

(2) serum intact parathyroid hormone (PTH) concentration

(3) sestamibi scan

(4) neck ultrasound

(5) concordance in the findings from the sestamibi and ultrasound scans

Parameter	Findings	Points
total serum calcium	< 3 mmol/L	0
	>= 3 mmol/L (>= 12 mg/dL)	1
serum intact PTH	< 2 times upper limit of normal	0
	>= 2 times the upper limit of normal	1
sestamibi scan	does not show 1 enlarged gland	0
	shows 1 enlarged gland	1
neck ultrasound	does not show 1 enlarged gland	0
	shows 1 enlarged gland	1
concordance of two scans	not concordant	0
	concordant (both show a single enlarged gland on the same side of the neck)	1

 

where:

• The sestamibi scan can show 0, 1 or multiple enlarged glands. No glands and multiple glands would be scored 0. Ditto for the ultrasound scan.

• I would think that the presence of multiple glands on sestamibi scan and/or ultrasound scan would make me think of multi-gland disease.

 

total score =

= SUM(points for all 5 parameters)

 

Interpretation:

• minimum score: 0

• maximum score: 5

• A patient with a score >= 3 can have minimally invasive surgery to remove the single implicated parathyroid gland. The patient does not require intra-operative PTH assay or additional imaging studies.

• A patient with a score < 3 should have additional testing to exclude multi-gland disease.

 

Performance:

• A score >= 3 was 100% specific but only 44% sensitivity for single gland disease.

• A score >= 2 had the maximum Youden score (specificity 89%, sensitivity 60%).

• A score >= 1 was the most sensitive (89%) but the lowest specificity (59%).