Major Haemorrhage during Vitamin K Antagonist Treatment: The Influence of Thyroid Hormone Levels

Effect of hypothyroidism on short-term outcomes after autologous and implant-based breast reconstruction

Hypothyroidism has high prevalence in elderly women, which overlaps with the patient population who opt for post-mastectomy breast reconstruction. While hypothyroidism was shown to impact outcomes in other surgeries, its effect on breast reconstruction has not been established. This study aimed to compare the short-term outcomes of patients with and without hypothyroidism who underwent autologous (ABR) and implant-based breast reconstruction (IBR), respectively. Patients having ABR or IBR were identified in the National Inpatient Sample from Q4 2015-2020. Multivariable logistic regressions were used to compare in-hospital outcomes between patients with and without hypothyroidism, adjusted for demographics, socioeconomic status, comorbidities, and hospital characteristics. There were 12,765 patients underwent ABR, where 1591 (12.46%) of them had hypothyroidism, while 17,670 patients had IBR with 1,984 (11.23%) having hypothyroidism. Hypothyroid patients had a higher risk of hemorrhage/hematoma (aOR = 1.254, 95 CI 1.079-1.457, p < 0.01) after ABR. However, there were no differences in terms of mortality and organ system complications, nor wound dehiscence, superficial/deep wound complications, seroma, flap revision, excessive scarring, venous thromboembolism, pulmonary embolism, vascular complications, infection, sepsis, transfer out, length of stay (LOS), nor hospital charge between patients with and without hypothyroidism after ABR. All postoperative outcomes were comparable between hypothyroid patients and controls after IBR. While breast reconstruction is generally safe for hypothyroid patients, preoperative screening for hypothyroidism may be beneficial for those undergoing ABR. In ABR, hypothyroidism correction and blood management may help prevent bleeding complications in hypothyroid patients. Future studies should explore the long-term prognosis of hypothyroid patients after breast reconstruction.

The interrelationship between pregnancy, venous thromboembolism, and thyroid disease: a hypothesis-generating review

Pregnancy induces physiological changes that affect the risk of thrombosis and thyroid disease. In this hypothesis-generating review, the physiological changes in the coagulation system and in thyroid function during a normal pregnancy are described, and the incidence of venous thromboembolism (VTE) and thyroid disease in and after a pregnancy are compared and discussed. Furthermore, evidence regarding the association between thyroid disease and VTE in non-pregnant individuals is scrutinized. In conclusion, a normal pregnancy entails hormonal changes, which influence the onset of VTE and thyroid disease. Current evidence suggests an association between thyroid disease and VTE in non-pregnant individuals. This review proposes the hypothesis that maternal thyroid disease associates with VTE in pregnant women and call for future research studies on this subject. If an association exists in pregnant women specifically, such findings may have clinical implications regarding strategies for thyroid function testing and potential thromboprophylaxis in selected individuals.

The influence of thyroid function on the coagulation system and its clinical consequences

Several studies indicate that low plasma levels of thyroid hormone shift the hemostatic system towards a hypocoagulable and hyperfibrinolytic state, whereas high levels of thyroid hormone lead to more coagulation and less fibrinolysis. Low levels of thyroid hormone thereby seem to lead to an increased bleeding risk, whereas high levels, by contrast, increase the risk of venous thromboembolism. Hypothyroidism leads to a higher incidence of acquired von Willebrand's syndrome and with increasing levels of free thyroxine, levels of fibrinogen, factor VIII and von Willebrand factor, amongst others, increase gradually, to the extent that they may lead to symptomatic venous thromboembolism in patients with hyperthyroidism. Here, we discuss the literature on the effect of thyroid hormone on the hemostatic system and the associated risk of bleeding and venous thromboembolism. Patients with hypothyroidism are at increased risk of developing bleeding complications, which could be relevant in patients undergoing invasive procedures. Furthermore, physicians should be aware of the possibility of hyperthyroidism as an underlying risk factor for venous thromboembolism, especially in unexplained cases. Clinical studies are needed to further investigate the significance for general practice of these findings. Besides the effects of hyperthyroidism on venous thromboembolism, its effects on embolism secondary to atrial fibrillation are described.

Plasma Levels of Free Thyroxine and Risk of Major Bleeding in Bariatric Surgery

BACKGROUND

In a recent study of patients using vitamin K antagonists, those with low free thyroxin (FT4) levels within the normal range had a 3- to 5-fold increased risk of major bleeding. We tested the hypothesis that low levels of preoperative FT4 within the reference range are associated with an increased risk of major bleeding during and after bariatric surgery.

METHODS

The charts of 2,872 consecutive patients undergoing bariatric surgery were retrospectively screened for bleeding episodes. Patients with major bleeding until 1 month after surgery were compared to randomly selected control patients without bleeding, in a ratio of 1:4. We evaluated the association between preoperative FT4 levels and the risk of major bleeding by logistic regression.

RESULTS

Seventy-two cases (2.5%) with major bleeding were identified and 288 controls were selected. The median plasma level of FT4 was 13 pmol/l (interquartile range: 12-14) in the cases as well as in the controls. No clear effect was observed of low levels of FT4 on the risk of major bleeding: odds ratio 1.48 (95% CI: 0.46-4.80) for patients with an FT4 level <11 pmol/l, 1.03 (0.49-2.18) for patients with an FT4 level <12 pmol/l, and 1.12 (0.65-1.94) for patients with an FT4 level <13 pmol/l as compared to patients with FT4 values greater than or equal to these cutoff levels.

INTERPRETATION

We did not observe an increased risk of major bleeding with low levels of FT4 in patients undergoing bariatric surgery.