Parathyroid localization by catheterization of large cervical and mediastinal veins to determine serum concentrations of intact parathyroid hormone

Background: We investigated whether increased protease activity explains the increased in vitro degradation of intact parathyroid hormone (iPTH) observed in serum when compared to EDTA plasma. Methods: Pre-dialysis blood samples for iPTH were taken from 11 patients with chronic renal failure and collected into plain glass tubes, tubes containing 200 KIU/mL aprotinin (a protease inhibitor) and EDTA tubes. All sample aliquots were separated at 20 min, 1 h, 2 h, 4 h, 8 h and 24 h post collection. Results: Over 24 h, iPTH concentrations remained unchanged in EDTA tubes. iPTH concentrations were significantly lower in both plain tubes ( P < 0·01) and aprotinin tubes ( P < 0·001) at 24 h when compared to the baseline sample (20 min). At 24 h, iPTH concentrations in EDTA tubes were higher than in plain tubes ( P < 0·001) and aprotinin tubes ( P < 0·01). The addition of aprotinin to plain tubes significantly reduced the degradation of iPTH ( P < 0·05) at 24 h. Conclusion: Aprotinin significantly reduces the in vitro degradation of iPTH in plain tubes at 24 h from 24·7% to 9·6%. We suggest that increased protease activity contributes to the decline in serum iPTH over time. As this is observed in serum and not plasma it suggests that the increased protease activity may be due to the clotting process.

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Serum intact parathyroid hormone levels in cats with chronic kidney disease

Pesquisa Veterinária Brasileira ◽

10.1590/s0100-736x2013000200015 ◽

2013 ◽

Vol 33 (2) ◽

pp. 229-235 ◽

Cited By ~ 4

Author(s):

Luciano H. Giovaninni ◽

Marcia M. Kogika ◽

Marcio D. Lustoza ◽

Archivaldo Reche Junior ◽

Vera A.B.F. Wirthl ◽

...

Keyword(s):

Chronic Kidney Disease ◽

Parathyroid Hormone ◽

Kidney Disease ◽

Stage Iv ◽

Control Group ◽

Intact Parathyroid Hormone ◽

Acid Base ◽

Acid Base Status ◽

Serum Ionized Calcium ◽

Progression Of Renal Disease

Chronic kidney disease (CKD) is frequently observed in cats and it is characterized as a multisystemic illness, caused by several underlying metabolic changes, and secondary renal hyperparathyroidism (SRHPT) is relatively common; usually it is associated with the progression of renal disease and poor prognosis. This study aimed at determining the frequency of SRHPT, and discussing possible mechanisms that could contribute to the development of SRHPT in cats at different stages of CKD through the evaluation of calcium and phosphorus metabolism, as well as acid-base status. Forty owned cats with CKD were included and divided into three groups, according to the stages of the disease, classified according to the International Renal Interest Society (IRIS) as Stage II (n=12), Stage III (n=22) and Stage IV (n=6). Control group was composed of 21 clinically healthy cats. Increased serum intact parathyroid hormone (iPTH) concentrations were observed in most CKD cats in all stages, and mainly in Stage IV, which hyperphosphatemia and ionized hypocalcemia were detected and associated to the cause for the development of SRHPT. In Stages II and III, however, ionized hypercalcemia was noticed suggesting that the development of SRHPT might be associated with other factors, and metabolic acidosis could be involved to the increase of serum ionized calcium. Therefore, causes for the development of SRHPT seem to be multifactorial and they must be further investigated, mainly in the early stages of CKD in cats, as hyperphosphatemia and ionized hypocalcemia could not be the only factors involved.

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