Copeptin Levels Before and After Transsphenoidal Surgery for Cushing Disease: A Potential Early Marker of Remission

Abstract

Context: Arginine-vasopressin and CRH act synergistically to stimulate secretion of ACTH. There is evidence that glucocorticoids act via negative feedback to suppress arginine-vasopressin secretion.

Objective: Our hypothesis was that a postoperative increase in plasma copeptin may serve as a marker of remission of Cushing disease (CD).

Design: Plasma copeptin was obtained in patients with CD before and daily on postoperative days 1 through 8 after transsphenoidal surgery. Peak postoperative copeptin levels and Δcopeptin values were compared among those in remission vs no remission.

Results: Forty-four patients (64% female, aged 7-55 years) were included, and 19 developed neither diabetes insipidus (DI) or syndrome of inappropriate anti-diuresis (SIADH). Thirty-three had follow-up at least 3 months postoperatively. There was no difference in peak postoperative copeptin in remission (6.1 pmol/L [4.3-12.1]) vs no remission (7.3 pmol/L [5.4-8.4], P = 0.88). Excluding those who developed DI or SIADH, there was no difference in peak postoperative copeptin in remission (10.2 pmol/L [6.9-21.0]) vs no remission (5.4 pmol/L [4.6-7.3], P = 0.20). However, a higher peak postoperative copeptin level was found in those in remission (14.6 pmol/L [±10.9] vs 5.8 (±1.4), P = 0.03]) with parametric testing. There was no difference in the Δcopeptin by remission status.

Conclusions: A difference in peak postoperative plasma copeptin as an early marker to predict remission of CD was not consistently present, although the data point to the need for a larger sample size to further evaluate this. However, the utility of this test may be limited to those who develop neither DI nor SIADH postoperatively.

Keywords: Cushing disease; copeptin; cortisol; remission.

Figure 1.

Preoperative plasma copeptin and sex. Preoperative plasma copeptin in all patients, comparing by sex. A higher preoperative plasma copeptin was found in males (7.0 pmol/L [5.1-9.6]) than in females (4.0 pmol/L [1.4-5.8], P = 0.004). Horizontal lines = median. Whiskers = 25th and 75th interquartile ranges.

Figure 2.

Preoperative plasma copeptin and BMI SDS. Association of preoperative plasma copeptin and BMI SDS in all patients. A BMI SDS was positively associated with a preoperative plasma copeptin (r_s = 0.54, P < 0.001). Shaded area = 95% confidence interval.

Figure 3.

(A) Peak postoperative plasma copeptin in all patients, comparing those in remission with no remission (6.1 pmol/L [4.3-12.1] vs 7.3 pmol/L [5.4-8.4], P = 0.88). (B) ΔCopeptin (preoperative plasma copeptin subtracted from postoperative peak plasma copeptin) in all patients, comparing those in remission with no remission (2.3 pmol/L [-0.5 to 8.2] vs 0.1 pmol/L [-0.1 to 2.2], P = 0.46). Horizontal lines = median. Whiskers = 25th and 75th interquartile ranges.

Figure 4.

(A) Peak postoperative plasma copeptin excluding those who developed DI or SIADH, comparing those in remission with no remission (10.2 pmol/L [6.9-21.0] vs 5.4 pmol/L [4.6-7.3], P = 0.20). (B) ΔCopeptin (preoperative plasma copeptin subtracted from postoperative peak plasma copeptin) excluding those who developed DI or SIADH, comparing those in remission with no remission (5.1 pmol/L [0.3-19.5] vs 1.1 pmol/L [-0.1 to 2.2], P = 0.39). Horizontal lines = median. Whiskers = 25th and 75th interquartile ranges.

Figure 5.

Plasma copeptin and serum cortisol vs postoperative day for patients who did not develop DI or SIADH. Plasma copeptin (indicated by closed circle) and serum cortisol (indicated by “x”). Results shown as (median, 95% CI).

Figure 6.

(A) Peak postoperative plasma copeptin, comparing those who developed DI, SIADH, or neither (P = 0.029 for comparison of all 3 groups). (B) ∆ Copeptin (preoperative plasma copeptin subtracted from postoperative peak plasma copeptin), comparing those who developed DI, SIADH, or neither (P = 0.043 for comparison of all 3 groups). Horizontal lines = median. Whiskers = 25th and 75th interquartile ranges. Top brackets = pairwise comparisons. P values presented are after Bonferroni correction for multiple comparisons.

Figure 7.

(A) Serum sodium and (B) plasma copeptin by POD and water balance status longitudinal data, adjusting for subgroups (ie, DI, SIADH, neither). Data points at point 0 on the x-axis indicate preoperative values. As expected, there was a group difference (P = 0.003) in serum sodium over time (all with DI were missing preoperative serum sodium), with the difference being driven by DI vs SIADH (P = 0.007), and SIADH vs neither (P = 0.012). There was no group difference in plasma copeptin over POD by water balance status (P = 0.16) over time.