Circulating ionized calcium and parathyroid hormone levels following coronary artery by-pass surgery.
In critically ill patients, hypocalcaemia is a common finding. Also variable derangements in the normally tight Ca2+-mediated control of the parathyroid hormone (PTH) secretion have been found. Utilizing coronary artery by-pass grafting (CABG) as a standardized model of severe trauma, 18 patients underwent determinations of blood levels of calcium, magnesium (Mg), ionized calcium (Ca2+), serum levels of intact PTH, procalcitonin (PCT) and the proinflammatory cytokines tumour necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6). Samples were collected before, directly after, the morning after and 5 days after surgery. A significant, but minor, decrease in blood Ca2+ levels (mean 0.04 mmol/L, p<0.05) was seen shortly after CABG, not accompanied by any significant change of serum PTH levels. This alteration of the Ca2+ control of the steady-state PTH levels contrasted with the maintenance of the PTH secretory response to a sequential citrate and calcium infusion (CiCa clamp), which was normal in two patients evaluated in the morning following surgery. Serum Mg levels were transiently increased after operation (+0.25 mmol/L, p<0.001) and correlated to the TNF-alpha (r=0.62, p <0.01) and PCT (r=0.67, p < 0.006) levels in the morning after surgery. Serum levels of IL-6 and TNF-alpha were significantly (p < 0.0001) increased immediately after surgery, while the peak in serum PCT levels (p < 0.001) occurred in the morning after CABG. Serum PTH levels correlated positively with IL-6 (r=0.68, p<0.008) 5 days after surgery. In conclusion, CABG caused a decrease in ionized calcium levels without a rise in steady-state PTH levels, but rapid changes in Ca2+ during CiCa clamping revealed a normal PTH secretory response. These findings might relate to elevated serum Mg levels, while a direct action of TNF-alpha or IL-6 on the PTH release seem less possible.
Carlstedt
F
F
Department of Internal Medicine, University Hospital of Uppsala, Sweden.
Lind
L
L
Joachimsson
P O
PO
Rastad
J
J
Wide
L
L
Ljunghall
S
S
D000368:Aged; D002116:Calcitonin / Q000097:blood; D015740:Calcitonin Gene-Related Peptide; D002118:Calcium / Q000097:blood*; D001026:Coronary Artery Bypass; D016207:Cytokines / Q000097:blood; D005260:Female; D006801:Humans; D008274:Magnesium / Q000097:blood; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D011498:Protein Precursors / Q000097:blood
C000606589:CALCA protein, human; D016207:Cytokines; D010281:Parathyroid Hormone; D011498:Protein Precursors; D002116:Calcitonin; D008274:Magnesium; D015740:Calcitonin Gene-Related Peptide; D002118:Calcium