Graves' ophthalmopathy as an indication increased the risk of hypoparathyroidism after bilateral thyroidectomy

Risk factors of transient and permanent hypoparathyroidism after thyroidectomy: a systematic review and meta-analysis

BACKGROUND

Postoperative hypoparathyroidism (hypoPT) is a common complication following thyroid surgery. However, current research findings on the risk factors for post-thyroid surgery hypoPT are not entirely consistent, and the same risk factors may have different impacts on transient and permanent hypoPT. Therefore, there is a need for a comprehensive study to summarize and explore the risk factors for both transient and permanent hypoPT after thyroid surgery.

MATERIALS AND METHODS

Two databases (PubMed and Embase) were searched from inception to 2024. The Newcastle-Ottawa Scale was used to rate study quality. Pooled odds ratios were used to calculate the relationship of each risk factor with transient and permanent hypoPT. Subgroup analyses were conducted for hypoPT with different definition-time (6 or 12 months). Publication bias was assessed using Begg's test and Egger's test.

RESULTS

A total of 19 risk factors from the 93 studies were included in the analysis. Among them, sex and parathyroid autotransplantation were the most frequently reported risk factors. Meta-analysis demonstrated that sex (female vs. male), cN stage, central neck dissection, lateral neck dissection, extent of central neck dissection (bilateral vs. unilateral), surgery [total thyroidectomy (TT) vs. lobectomy], surgery type (TT vs. sub-TT), incidental parathyroidectomy, and pathology (cancer vs. benign) were significantly associated with transient and permanent hypoPT. Preoperative calcium and parathyroid autotransplantation were only identified as risk factors for transient hypoPT, while preoperative PTH was a protective factor. Additionally, node metastasis and parathyroid in specimen were associated with permanent hypoPT.

CONCLUSION

The highest risk of hypoPT occurs in female thyroid cancer patients with lymph node metastasis undergoing TT combined with neck dissection. The key to preventing postoperative hypoPT lies in the selection of surgical approach and intraoperative protection.

The Association of Discolored Parathyroid Glands and Hypoparathyroidism Following Total Thyroidectomy

BACKGROUND

It remains uncertain whether a parathyroid gland (PG) that appears darkened or severely bruised but still has an attached vascular pedicle should be left in situ or taken out and auto-transplanted following total thyroidectomy. Our study aimed to examine the impact of discolored PGs (DPGs) on short- and long-term hypoparathyroidism.

METHODS

One hundred and three patients who underwent total thyroidectomy with 4 clearly identified PGs were analyzed. Location (superior/inferior) and color of each PG were recorded. Patients without DPG were grouped into I while those with 1-2 DPGs and ≥3 DPGs were grouped into II and III, respectively. Transient hypoparathyroidism meant adjusted Ca <2.00 mol/L 24 h after surgery and/or need for supplements. Protracted hypoparathyroidism meant a subnormal PTH at 4-6 weeks and/or supplements >6 weeks. Permanent hypoparathyroidism meant supplements ≥1 year.

RESULTS

Relative to I, group III had greater adjusted Ca drop at postoperative 1-h (p = 0.012), 24-h (p < 0.001) and lower day-1 PTH (p = 0.015). Having ≥3 DPGs (OR 14.00, 95 % CI 1.575-124.474, p = 0.018) was an independent factor of transient hypoparathyroidism. However, permanent hypoparathyroidism rate was higher than in group I than II (p = 0.019). Eight patients (25.8 %) in group I had undetectable day-1 PTH, while none in group III had undetectable day-1 PTH. Graves' disease/toxic goiter (OR 15.166, 95 % CI 2.594-88.661, p = 0.003) and excised gland weight (OR 1.028, 95 % CI 1.010-1.046, p = 0.003) were independent factors of ≥3 DPGs.

CONCLUSIONS

PG discoloration is associated with transient hypoparathyroidism while normal colored PG with seemingly adequate blood supply does not always imply functionally normal gland. These findings highlights the need for a real-time intraoperative method to assess PG viability.

Indocyanine green fluorescence angiography for quantitative evaluation of in situ parathyroid gland perfusion and function after total thyroidectomy

BACKGROUND

Because the fluorescent light intensity on an indocyanine green fluorescence angiography reflects the blood perfusion within a focused area, the fluorescent light intensity in the remaining in situ parathyroid glands may predict postoperative hypocalcemia risk after total thyroidectomy.

METHODS

Seventy patients underwent intraoperative indocyanine green fluorescence angiography after total thyroidectomy. Any parathyroid glands with a vascular pedicle was left in situ while any parathyroid glands without pedicle or inadvertently removed was autotransplanted. After total thyroidectomy, an intravenous 2.5 mg indocyanine green fluorescence angiography was given and real-time fluorescent images of the thyroid bed were recorded using the SPY imaging system (Novadaq, Ontario, Canada). The fluorescent light intensity of each indocyanine green fluorescence angiography as well as the average and greatest fluorescent light intensity in each patient were calculated. Postoperative hypocalcemia was defined as adjusted calcium <2.00 mmol/L within 24 hours.

RESULTS

The fluorescent light intensity between discolored and normal-looking indocyanine green fluorescence angiographies was similar (P = .479). No patients with a greatest fluorescent light intensity >150% developed postoperative hypocalcemia while 9 (81.8%) patients with a greatest fluorescent light intensity ≤150% did. Similarly, no patients with an average fluorescent light intensity >109% developed PH while 9 (30%) with an average fluorescent light intensity ≤109% did. The greatest fluorescent light intensity was more predictive than day-0 postoperative hypocalcemia (P = .027) and % PTH drop day-0 to 1 (P < .001).

CONCLUSION

Indocyanine green fluorescence angiography is a promising operative adjunct in determining residual parathyroid glands function and predicting postoperative hypocalcemia risk after total thyroidectomy.

Failure of radioactive iodine in the treatment of hyperthyroidism

BACKGROUND

Persistent or recurrent hyperthyroidism after treatment with radioactive iodine (RAI) is common and many patients require either additional doses or surgery before they are cured. The purpose of this study was to identify patterns and predictors of failure of RAI in patients with hyperthyroidism.

METHODS

We conducted a retrospective review of patients treated with RAI from 2007 to 2010. Failure of RAI was defined as receipt of additional dose(s) and/or total thyroidectomy. Using a Cox proportional hazards model, we conducted univariate analysis to identify factors associated with failure of RAI. A final multivariate model was then constructed with significant (p < 0.05) variables from the univariate analysis.

RESULTS

Of the 325 patients analyzed, 74 patients (22.8 %) failed initial RAI treatment, 53 (71.6 %) received additional RAI, 13 (17.6 %) received additional RAI followed by surgery, and the remaining 8 (10.8 %) were cured after thyroidectomy. The percentage of patients who failed decreased in a stepwise fashion as RAI dose increased. Similarly, the incidence of failure increased as the presenting T3 level increased. Sensitivity analysis revealed that RAI doses <12.5 mCi were associated with failure while initial T3 and free T4 levels of at least 4.5 pg/mL and 2.3 ng/dL, respectively, were associated with failure. In the final multivariate analysis, higher T4 (hazard ratio [HR] 1.13; 95 % confidence interval [CI] 1.02-1.26; p = 0.02) and methimazole treatment (HR 2.55; 95 % CI 1.22-5.33; p = 0.01) were associated with failure.

CONCLUSIONS

Laboratory values at presentation can predict which patients with hyperthyroidism are at risk for failing RAI treatment. Higher doses of RAI or surgical referral may prevent the need for repeat RAI in selected patients.

How useful are perioperative biochemical parameters in predicting the duration of calcium and/or vitamin D supplementation after total thyroidectomy?

BACKGROUND

Oral calcium and calcitriol are often prescribed after total thyroidectomy to avoid biochemical and/or symptomatic hypocalcemia. We aimed to identify independent perioperative factors that correlated with the duration of calcium and/or calcitriol supplementation after total thyroidectomy.

METHODS

Of 271 eligible patients, 48 (17.7 %) required calcium and/or calcitriol supplements on discharge. Patients were gradually weaned from the supplementation by one surgeon according to a biweekly algorithm based on serum calcium (Ca). Duration of supplementation was calculated from the date of operation to the date of ceasing all supplementation without biochemical hypocalcemia (i.e., serum adjusted Ca ≥ 8.44 mg/dL). The Cox regression analysis was performed to identify independent perioperative factors for duration of supplementation. The best cut-off value for these independent factors was determined by the receiver characteristic curve.

RESULTS

In the multivariate analysis, parathyroid hormone (PTH) at skin closure (PTH-SC) (RR 1.742, 95 % CI 1.080-2.810) and on postoperative day 1 adjusted Ca (Ca-D1) (RR 77.526, 95 % CI 3.600-1669.57) were the only two independent determinants for shorter duration before ceasing all supplementation. The best cut-off values in predicting supplementation ≥ 6 months for PTH-SC and Ca-D1 were 7.08 pg/mL (sensitivity = 100 %, specificity = 60.5 %, PPV = 40.0 % and NPV = 100 %) and 7.88 mg/dL (sensitivity = 90.0 %, specificity = 55.3 %, PPV = 34.6 % and NPV = 95.5 %), respectively.

CONCLUSIONS

Both PTH-SC and Ca-D1 were independently associated with the duration of supplementation after total thyroidectomy. Almost all patients with PTH-SC ≥ 7.08 pg/mL or Ca-D1 ≥ 7.88 mg/dL did not require supplementation ≥ 6 months whereas about one third of patients with PTH-SC <7.08 pg/mL or Ca-D1 <7.88 mg/dL required supplementation ≥ 6 months.

Identifying predictors of a difficult thyroidectomy

BACKGROUND

A Thyroidectomy Difficulty Scale (TDS) was previously developed that identified more difficult operations, which correlated with longer operative times and higher complication rates. The purpose of this study was to identify preoperative variables predictive of a more difficult thyroidectomy using the TDS.

METHODS

A four item, 20-point TDS, was used to score the difficulty of thyroid operations. Patient and disease factors were recorded for each patient. Difficult thyroidectomy and non-difficult thyroidectomy (NDT) patients were compared. A final multivariate logistic regression model was constructed with significant (P<0.05) variables from a univariate analysis.

RESULTS

A total of 189 patients were scored using TDS. Of them, 69 (36.5%) suffered from hyperthyroidism, 42 (22.2%) from Hashimotos, 34 (18.0%) from thyroid cancer, and 36 (19.0%) from multinodular goiter. Among hyperthyroid patients, the DT group had a greater number preoperatively treated with Lugols potassium iodide (81.6% DT versus 58.1% NDT, P=0.032), presence of ophthalmopathy (31.6% DT versus 9.7% NDT, P=0.028), and presence of (>4 IU/mL) antithyroglobulin antibodies (34.2% DT versus 12.9% NDT, P=0.05). Using multivariate analysis, hyperthyroidism (odds ratio [OR], 4.35, 95% confidence interval [CI], 1.23-15.36, P=0.02), presence of antithyroglobulin antibody (OR, 3.51, 95% CI, 1.28-9.66, P=0.015), and high (>150 ng/mL) thyroglobulin (OR, 2.61, 95% CI, 1.06-6.42, P=0.037) were independently associated with DT.

CONCLUSIONS

Using TDS, we demonstrated that a diagnosis of hyperthyroidism, preoperative elevation of serum thyroglobulin, and antithyroglobulin antibodies are associated with DT. This tool can assist surgeons in counseling patients regarding personalized operative risk and improve OR scheduling.

Thyroidectomy as primary treatment optimizes body mass index in patients with hyperthyroidism

OBJECTIVE

The purpose of this study was to determine how the timing of thyroidectomy influenced postoperative weight change.

METHODS

We conducted a two-institution study, identifying patients treated with total thyroidectomy for hyperthyroidism. Patients were classified as 'early' if they were referred for surgery as the first treatment option, or 'delayed' if they were previously treated with radioactive iodine (RAI). Groups were compared with the Student's t-test or χ (2) test where appropriate.

RESULTS

There were 204 patients undergoing thyroidectomy for hyperthyroidism. Of these, 171 patients were classified as early and 33 were classified as delayed. Overall, patients gained 6.0 % ± 0.8 of their preoperative body weight at last follow-up. Preoperative body mass indexes (BMIs) were similar between groups (p = 0.98), and the median follow-up time was 388 days (range 15-1,584 days). Both groups gained weight until they achieved a normal thyroid-stimulating hormone (TSH) postoperatively. After achieving a normal TSH, the early group stabilized or lost weight (-0.2 lbs/day), while the delayed group continued to gain weight (0.02 lbs/day; p = 0.61). At last follow-up, there were significantly more patients in the delayed group who increased their BMI category compared with the early group (42.4 vs. 21.6 %; p = 0.01). Twice as many patients in the delayed group moved up or into an unhealthy BMI category (overweight or obese) compared with the early group (39.4 vs. 19.3 %; p = 0.01).

CONCLUSIONS

Compared with patients initially treated with RAI, patients with hyperthyroidism who underwent surgery as the first treatment were less likely to become overweight or obese postoperatively.

Evaluating the efficacy of primary treatment for graves' disease complicated by thyrotoxic periodic paralysis

Objective. Thyrotoxic periodic paralysis (TPP) is a potentially life-threatening complication of Graves' disease (GD). The present study compared the long-term efficacy of antithyroid drugs (ATD), radioactive iodine (RAI), and surgery in GD/TPP. Methods. Sixteen patients with GD/TPP were followed over a 14-year period. ATD was generally prescribed upfront for 12-18 months before RAI or surgery was considered. Outcomes such as thyrotoxic or TPP relapses were compared between the three modalities. Results. Eight (50.0%) patients had ATD alone, 4 (25.0%) had RAI, and 4 (25.0%) had surgery as primary treatment. Despite being able to withdraw ATD in all 8 patients for 37.5 (22-247) months, all subsequently developed thyrotoxic relapses and 4 (50.0%) had ≥1 TPP relapses. Of the four patients who had RAI, two (50%) developed thyrotoxic relapse after 12 and 29 months, respectively, and two (50.0%) became hypothyroid. The median required RAI dose to render hypothyroidism was 550 (350-700) MBq. Of the 4 patients who underwent surgery, none developed relapses but all became hypothyroid. Conclusion. To minimize future relapses, more definitive primary treatment such as RAI or surgery is preferred over ATD alone. If RAI is chosen over surgery, a higher dose (>550 MBq) is recommended.

A review of risk factors and timing for postoperative hematoma after thyroidectomy: is outpatient thyroidectomy really safe?

Background

Although postoperative hematoma after thyroidectomy is uncommon, patients traditionally have been advised to stay overnight in the hospital for monitoring. With the growing demand for outpatient thyroidectomy, we assessed its safety and feasibility by evaluating the potential risk factors and timing of postoperative hematoma after thyroidectomy.

Methods

From 1995–2011, 3,086 consecutive patients underwent thyroidectomy at our institution; of these, 22 (0.7 %) developed a postoperative hematoma that required surgical reexploration (group I). Potential risk factors were compared between group I and those without hematoma (n = 3,045) or with hematoma but not requiring reexploration (n = 19; group II). Variables that were significant in the univariate analysis were entered into multivariate analysis by binary logistic regression analysis.

Results

Group I was significantly more likely to have undergone previous thyroid operation than group II (27.3 vs. 8.2 %, p = 0.007). The median weight of excised thyroid gland (71.8 vs. 40 g, p = 0.018) and the median size of the dominant nodule (4.1 vs. 3 cm, p = 0.004) were significantly greater in group I than group II. Previous thyroid operation (odds ratio (OR) = 4.084; 95 % confidence interval (CI), 1.105–15.098; p = 0.035) and size of dominant nodule (OR = 1.315; 95 % CI, 1.024–1.687; p = 0.032) were independent factors for hematoma. Sixteen (72.7 %) had hematoma within 6 h, whereas the other 6 (27.3 %) had hematoma at 6–24 h.

Conclusions

Previous thyroid operation and large dominant nodule were independent risk factors for hematoma requiring surgical reexploration. Given that a quarter of hematoma occurred between 6 to 24 h after surgery, routine outpatient thyroidectomy could not be recommended.

A prospective evaluation of quick intraoperative parathyroid hormone assay at the time of skin closure in predicting clinically relevant hypocalcemia after thyroidectomy

Background

Post-thyroidectomy hypocalcemia is a major contributing factor in delayed hospital discharge and dissuading surgeons from ambulatory thyroidectomy. We prospectively evaluated the accuracy and reliability of quick parathyroid hormone level measurement at skin closure (PTH-SC) in predicting clinically relevant hypocalcemia (i.e., patients requiring calcium ± calcitriol supplements on hospital discharge).

Methods

Of the 117 patients who underwent a total or completion total thyroidectomy and PTH-SC, 17 (14.5 %) had hypocalcemic symptoms or adjusted calcium <1.90 mmol/L requiring calcium and/or calcitriol supplements on discharge. Serum calcium was checked regularly in the perioperative period until stabilization and an additional quick PTH was checked on the following morning (PTH-D1). Univariate and multivariate analyses were performed to evaluate potential preoperative clinicopathologic factors and postoperative day 0 biochemical indicators. Youden’s index and the area under the ROC curve (AUC) were used to determine the best cutoff value and predictability of significant variables or criteria, respectively.

Results

In the multivariate analysis, low preoperative adjusted calcium (p = 0.041) and low PTH-SC (p = 0.001) were the two independent variables associated with hypocalcemia. PTH-SC (≤1 or >1 pmol/L) had a higher specificity (95.0 %) and AUC (0.887) than serial calcium monitoring or PTH-D1 alone. Although 3/98 of patients with PTH-SC >1 pmol/L required calcium supplements on discharge, they required only the minimum amount to maintain normocalcemia.

Conclusion

PTH-SC is an accurate and reliable means of predicting clinically relevant hypocalcemia. It would be reasonable to discharge those with PTH-SC >1 pmol/L on the same operative day as the risk of life-threatening hypocalcemia would seem unlikely.