Hypocalcemia and parathyroid hormone secretion in critically ill patients.
OBJECTIVE
To investigate possible causes of hypocalcemia and to assess parathyroid hormone (PTH) secretion in intensive care unit (ICU) patients.


METHODS
Combined cross-sectional and prospective study.


METHODS
ICU in a university hospital.


METHODS
Thirteen patients with sepsis and 13 patients who underwent major surgery.


METHODS
None.


RESULTS
Calcium metabolic indices were investigated during the first 24 hrs in the ICU and after 2 days. Eight of the surgical patients and five of the septic patients were subjected to a citrate/calcium infusion on day 1 in the ICU, to study the dynamics of PTH secretion. The blood ionized calcium (Ca2+) concentration was generally low in the septic patients (mean +/- SD, 1.03+/-0.08 mmol/L; reference value, 1.10-1.30) and increased, but not normalized, after 2 days. Hypocalcemia was only occasionally seen in the surgical patients. In the septic patients, urinary excretion of calcium was low; and, in both patient groups, elevated concentrations of two markers of bone resorption, deoxypyridinoline and ICTP (serum carboxy-terminal cross-linked telopeptide of type I collagen), were found. In cases of sepsis, the concentrations of proinflammatory cytokines were high (394+/-536 pg/mL for tumor necrosis factor-alpha and 5676+/-5190 pg/mL for interleukin-6, both normally <10-20). The Ca2+ concentration was inversely related to tumor necrosis factor-alpha and interleukin-6 (r2 = .35-.42; p<.01), as well as to procalcitonin (r2 = .71; p<.01). Despite normocalcemia in the surgical patients, serum PTH concentrations were elevated in both patient groups (97 and 109 ng/L) (reference value, <55 ng/L), both on day 1 and day 3 in the ICU. The citrate/calcium infusion revealed an increased secretory response of PTH to lowered Ca2+ concentrations in both groups of patients (p<.05), when compared with matched healthy controls.


CONCLUSIONS
Hypocalcemia was common in septic ICU patients and was not the result of an increased urinary excretion of calcium or of an attenuated bone resorption, but seemed related to the inflammatory response. An increased PTH secretion was found in both patient groups.
Lind
L
L
Department of Internal Medicine, University Hospital of Uppsala, Sweden.
Carlstedt
F
F
Rastad
J
J
Stiernström
H
H
Stridsberg
M
M
Ljunggren
O
O
Wide
L
L
Larsson
A
A
Hellman
P
P
Ljunghall
S
S
D018806:APACHE; D015415:Biomarkers / Q000097:blood / Q000652:urine; D001862:Bone Resorption; D002118:Calcium / Q000097:blood / Q000378:metabolism* / Q000652:urine; D003430:Cross-Sectional Studies; D016207:Cytokines / Q000097:blood; D005260:Female; D006801:Humans; D006996:Hypocalcemia / Q000097:blood / Q000209:etiology*; D007249:Inflammation; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood / Q000378:metabolism*; D011183:Postoperative Complications / Q000097:blood*; D011446:Prospective Studies; D018805:Sepsis / Q000097:blood / Q000378:metabolism*; D013997:Time Factors
D015415:Biomarkers; D016207:Cytokines; D010281:Parathyroid Hormone; D002118:Calcium