Early prediction of hypocalcemia after thyroidectomy using parathyroid hormone: an analysis of pooled individual patient data from nine observational studies.
BACKGROUND
Monitoring for hypocalcemia after thyroidectomy, using only symptoms and serum calcium levels, can delay the discharge of patients who will remain normocalcemic and can delay the treatment of hypocalcemic patients.


METHODS
We conducted a systematic search for articles describing use of parathyroid hormone (PTH) assay, checked within hours of completing thyroidectomy, to predict postoperative symptomatic hypocalcemia. Studies were excluded if all patients were treated with postoperative calcium, or if early PTH values were used to alter management of the patient. Individual patient data (perioperative PTH and calcium levels, development of hypocalcemia) were obtained for 457 patients from the corresponding authors of 9 studies and pooled to yield the following results.


RESULTS
PTH, checked at three time periods after removal of the thyroid gland (0 to 20 minutes, 1 to 2 hours, and 6 hours), was substantially lower in patients who became hypocalcemic compared with those who remained normocalcemic. The accuracy of PTH in determining hypocalcemia increased with time and was excellent when checked 1 to 6 hours postoperatively. A single PTH threshold (65% decrease compared with preoperative level), checked 6 hours after completing thyroidectomy, had a sensitivity of 96.4% and specificity of 91.4% in detecting postoperative hypocalcemia.


CONCLUSIONS
PTH assay, when checked 1 to 6 hours after thyroidectomy, has excellent accuracy in determining which patients will become symptomatically hypocalcemic. Routine use of this assay should be considered because it may allow earlier discharge of the normocalcemic patient and earlier identification of patients requiring treatment of postthyroidectomy hypocalcemia.
Department of Otolaryngology-Head and Neck Surgery, Boston University Medical Center, Boston, MA, USA. pieter.noordzij@bmc.org
J Pieter
JP
Noordzij
Stephanie L
SL
Lee
Victor J
VJ
Bernet
Richard J
RJ
Payne
Seth M
SM
Cohen
Ian K
IK
McLeod
Michael P
MP
Hier
Martin J
MJ
Black
Paul D
PD
Kerr
Melanie L
ML
Richards
Chung Yau
CY
Lo
Marco
M
Raffaelli
Rocco
R
Bellantone
Celestino P
CP
Lombardi
James I
JI
Cohen
Mary S
MS
Dietrich
D006801:Humans; D006996:Hypocalcemia / Q000097:blood* / Q000209:etiology; D010281:Parathyroid Hormone / Q000097:blood*; D011237:Predictive Value of Tests; D012372:ROC Curve; D013965:Thyroidectomy / Q000009:adverse effects*; D013997:Time Factors
C470125:PTH protein, human; D010281:Parathyroid Hormone