Haemostasis in hypothyroidism

Which patients on a gynecologic oncology service will require perioperative transfusion? A single-center retrospective cohort study

The purpose of this study was to determine which patient- or surgery-related factors are predictive of need for perioperative transfusion to avoid obtaining unnecessary pre-operative type and screens (T&S). We conducted an observational retrospective cohort study of 1200 women ≥ 18 years old undergoing gynecologic surgery for benign, possibly benign, or malignant indications on a gynecologic oncology service at a university medical center from 2009-2016. A logistic regression model was used to examine patient-related and surgery-related variables predictive of outcome of transfusion. Independent variables included patient demographics, comorbidities, and surgical indication surgical route, and surgical type. Dependent variable was transfusion outcome (T&S only, conversion to type and cross (T&C), or transfusion). Eight hundred ninety-nine (74.9%) women underwent pre-operative T&S, of which 118 (9.8%) were converted to T&C, and 80 (6.7%) received a transfusion of blood or blood products. Cancer indication, major surgery, and preoperative hematocrit less than 36% were significantly associated with need for transfusion (P = 0.002, P < 0.0001, P < 0.0001, respectively). Patients with a benign indication undergoing minor procedures and with normal preoperative hematocrit are least likely to require transfusion.

Thyroid Diseases Are an Underestimated Risk Factor for Cerebral Venous Sinus Thrombosis

Introduction: Cerebral venous sinus thrombosis (CVST) is a rare disease that generally accounts for just 1% of all strokes. Of the multiple risk factors that have been identified, the most common are genetic or acquired thrombophilia and the use of oral contraceptives, while the less common include local infections and mechanical causes. Thyroid diseases have been described as rare risk factors for CVST (<2% of all cases), without exact knowledge of the underlying pathophysiology. This retrospective study aimed to re-evaluate the relevance of thyroid disease as risk factor for CVST, with particular emphasis on hyperthyroidism.

Patients and Methods: Confirmed cases of CVST were (re-)evaluated in terms of risk factors including thyroid parameters. Results were compared to previous data from the International Study on CVST.

Results: Between 1996 and 2016, 182 patients with confirmed CVST were treated in our hospital with a median age of 44 years and a female proportion of 74.7%. Genetic or acquired thrombophilia along with the use of oral contraceptives were found to be the most common risk factors. Thyroid diseases were present in 20.9% of CVST patients; this included patients with previous (9.9%) and current thyroid dysfunction (11%).

Discussion and Conclusions: Thyroid diseases may represent a more common risk factor for CVST than previously described. This holds true even if patients with current thyroid dysfunction are purely taken into account. However, 58% of patients had more than one additional risk factor, suggesting a multifactorial hypercoagulability.

Clinical Trials Register: Registered at the German Clinical Trials Register: http://www.drks.de, DRKS00017044.

An Unexpected Cause of Catastrophic Bleeding: A Case Report

Profound hypothyroidism has been linked to mild bleeding diathesis such as easy bruising and menorrhagia. Bleeding tendency depends on the severity of hypothyroidism. Those with moderate disease are prone to thrombotic events, while those with profound hypothyroidism are prone to bleeding. This paper reports a case of severe intraoperative bleeding during elective rhinoplasty in a patient with missed profound hypothyroidism. The clinical and laboratory findings are presented with a review of the literature. A 43-year-old female was admitted for an elective rhinoplasty. In the theater, the patient developed massive bleeding at the beginning of surgery. On the next day, the patient was discharged home for further assessment with a massive bruise all over her face. Upon history taking, the patient denied any drug abuse or previous bleeding episode or family history of bleeding disorder. Surprisingly, a transverse scar was noted at the lower part of the neck. The patient admitted that she had thyroidectomy done 2 years ago, and she was kept on thyroxine replacement and stopped it by herself 18 months ago. Thyroid-stimulating hormone (TSH) was 70 mU/L, and von Willebrand factor antigen/ristocetin cofactor was normal. A diagnosis of acquired von Willebrand syndrome type 1 was made. The patient was kept on thyroxine 150 µg/day. Six weeks later, TSH was 0.8 mU/L, and all bleeding parameters were corrected. A careful history taking and general examination looking for hypothyroidism is crucial in the preoperative assessment. It might be prudent to include thyroid function test in the routine preoperative investigation of all patients.

Subclinical Hyperthyroidism Could Predict Poor Outcomes in Patients With Acute Ischemic Stroke Treated With Reperfusion Therapy

Background: Evidence for the effect of subclinical thyroid dysfunction on the prognosis of patients suffering from acute ischemic stroke and receiving reperfusion therapy remains controversial. We aimed to investigate the association between subclinical thyroid dysfunction and the outcomes of patients with acute ischemic stroke who were treated with reperfusion therapy.

Methods: One hundred fifty-six consecutively recruited patients with acute ischemic stroke receiving reperfusion therapy (intravenous thrombolysis, intraarterial thrombectomy and combined intravenous thrombolysis and intraarterial thrombectomy) were included in this prospective observational study. We divided patients with subclinical thyroid dysfunction into the following 2 groups and defined a euthyroid group: subclinical hyperthyroidism (a thyroid-stimulating hormone level <0.35 μU/mL), subclinical hypothyroidism (a thyroid-stimulating hormone level >4.94 μU/mL), and a euthyroid state (0.35 μU/mL ≤ thyroid-stimulating hormone level ≤ 4.94 μU/mL). Patients with overt thyroid dysfunction were excluded. The primary outcome was functional disability at 3 months (modified Rankin Scale, mRS), and the secondary outcome was successful reperfusion. A multivariate analysis was performed to evaluate the associations between subclinical thyroid dysfunction and the primary and secondary outcomes.

Results: The subclinical hyperthyroidism group appeared to have poor functional outcomes, but the differences were not significant. However, compared with patients in the euthyroid state, patients with subclinical hyperthyroidism had an increased risk of poor functional outcomes at 3 months after a stroke (adjusted odds ratio [OR] 2.50, 95% confidence interval [CI] 1.01–6.14 for a mRS score of 3 to 6) and a decreased rate of successful reperfusion after reperfusion therapy (OR 0.13, 95% CI 0.04–0.43).

Conclusion: Subclinical hyperthyroidism may be independently associated with a poor prognosis at 3 months and unsuccessful reperfusion in patients with acute ischemic stroke receiving reperfusion therapy.

Comparison of Mean Platelet Volume, Platelet Count, Neutrophil/ Lymphocyte Ratio and Platelet/Lymphocyte Ratio in the Euthyroid, Overt Hypothyroid and Subclinical Hyperthyroid Phases of Papillary Thyroid Carcinoma

INTRODUCTION

Thyroid hormones are essential for the normal development, differentiation, metabolic balance and physiological function of all tissues. Mean platelet volume (MPV) indicates mean platelet size and reflects platelet production rate and stimulation. Increased platelet size has been observed in association with known cardiovascular risk factors. The neutrophil/lymphocyte ratio (NLR) and platelet/lymphocyte ratio (PLR) are known markers of the systemic inflammatory response. This study aimed to investigate the effect of thyroid hormone changes by comparing platelet count, MPV values, NLR and PLR in thyroid papillary carcinoma.

METHODS

Forty-nine females and nine males comprising a total of 58 patients were included in the study. Clinical and laboratory parameters of patients were recorded in the following three phases of the disease: euthyroid phase (before thyroid surgery), overt hypothyroid (OH) phase (before radioactive iodine [RAI] treatment) and subclinical hyperthyroid (SCH) phase (six months after RAI treatment).

RESULTS

The mean thyroid-stimulating hormone (TSH) values of the patients in the euthyroid, OH and SCH phases were 1.62±1.17, 76.4±37.5 and 0.09±0.07 µIU/mL, respectively. The mean MPV values of the patients in the euthyroid, OH and SCH phases were 9.45±1.33, 9.81±1.35 and 9.96±1.21 fL, respectively. MPV was significantly higher in the SCH phase than in the euthyroid phase (p=0.013). Platelet count, NLR and PLR were not statistically different between the euthyroid, OH and SCH phases.

CONCLUSION

The results of this study demonstrated that the levels of MPV increased significantly in the SCH phase in patients with papillary thyroid carcinoma (PTC), and increased MPV values contributed to increased risk of cardiovascular complications. These findings suggest that MPV can be a valuable, practical parameter for monitoring the haemostatic condition in thyroid disorders. No significant difference was observed in platelet count, NLR and PLR in all stages of PTC.

Myxedema Crisis Presenting with Seizures: A Rare Life-Threatening Presentation-A Case Report and Review of the Literature

Myxedema crisis is a life-threatening extreme form of hypothyroidism with a high mortality rate if left untreated. Myxedema crisis is commonly seen in older patients, especially in women, and is associated with signs of hypothyroidism, hypothermia, hyponatraemia, hypercarbia, and hypoxemia. Patients might present with different organ specific symptoms. Seizures are a recognized but rare manifestation of myxedema with a very high mortality rate. Prompt diagnosis and appropriate management may improve the prognosis. Many contributory factors may involve development of seizures in a patient with myxedema. Hyponatraemia is one such cause, which is seen in moderate-severe form in the background of myxedema. We report an elderly male who presented with generalized tonic clonic seizure preceded by memory impairment and drowsiness. He had moderate hyponatraemia and very high thyroid stimulatory hormone levels in association with low free thyroxin levels. Diagnosis of myxedema crisis was made and patient was successfully treated with sodium correction and thyroid hormone replacement.

Hemostasis in Hypothyroidism and Autoimmune Thyroid Disorders

CONTEXT

There are contradictory results on the effect of hypothyroidism on the changes in hemostasis. Inadequate population-based studies limited their clinical implications, mainly on the risk of venous thromboembolism (VTE). This paper reviews the studies on laboratory and population-based findings regarding hemostatic changes and risk of VTE in hypothyroidism and autoimmune thyroid disorders.

EVIDENCE ACQUISITION

A comprehensive literature search was conducted employing MEDLINE database. The following words were used for the search: Hypothyroidism; thyroiditis, autoimmune; blood coagulation factors; blood coagulation tests; hemostasis, blood coagulation disorders; thyroid hormones; myxedema; venous thromboembolism; fibrinolysis, receptors thyroid hormone. The papers that were related to hypothyroidism and autoimmune thyroid disorder and hemostasis are used in this review.

RESULTS

Overt hypothyroidism is more associated with a hypocoagulable state. Decreased platelet count, aggregation and agglutination, von Willebrand factor antigen and activity, several coagulation factors such as factor VIII, IX, XI, VII, and plasminogen activator-1 are detected in overt hypothyrodism. Increased fibrinogen has been detected in subclinical hypothyroidism and autoimmune thyroid disease rendering a tendency towards a hypercoagulability state. Increased factor VII and its activity, and plasminogen activator inhibitor-1 are among several findings contributing to a prothrombotic state in subclinical hypothyroidism.

CONCLUSIONS

Overt hypothyroidism is associated with a hypocoagulable state and subclinical hypothyroidism and autoimmune thyroid disorders may induce a prothrombotic state. However, there are contradictory findings for the abovementioned thyroid disorders. Prospective studies on the risk of VTE in various levels of hypofunctioning of the thyroid and autoimmune thyroid disorders are warranted.

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.

Prognostic value of thyroid-stimulating hormone within reference range in patients with coronary artery disease

BACKGROUND

Thyroid-stimulating hormone (TSH) in the upper part of reference range is associated with cardio-metabolic disorders. The association of TSH within reference range with prognosis of patients with coronary artery disease (CAD) after percutaneous coronary intervention (PCI) remains poorly investigated.

METHODS

The study included 8010 consecutive patients with CAD who were treated with PCI. All patients had a TSH level within reference range (0.3 to 4.0 mU/L). The primary outcome was 3-year all-cause mortality.

RESULTS

TSH tertiles were: 1st tertile (0.3 mU/L to <1.02 mU/L; n=2694), 2nd tertile (1.02 mU/L to <1.67 mU/L; n=2654) and 3rd tertile (1.67 mU/L to 4.00 mU/L; n=2662). The primary outcome (3-year mortality) occurred in 753 patients: 240 deaths in the 1st, 227 deaths in the 2nd and 286 deaths in the 3rd TSH tertile (Kaplan-Meier estimates of mortality 10.2%, 9.8% and 12.3%; adjusted hazard ratio [HR]=1.31, 95% confidence interval [CI] 1.04-1.66 for each tertile increase). TSH level was associated with 30-day mortality (mortality estimates, 1.6% in the 1st, 1.6% in the 2nd and 3.5% in the 3rd TSH tertile; adjusted HR=2.30 [1.33-3.97] for each tertile increase) but not with 30-day to 3-year mortality (mortality estimates, 8.6% in the 1st, 8.2% in the 2nd and 8.8% in the 3rd TSH tertile; P=0.603). The incidence of cardiogenic shock or peri-PCI bleeding was increased in patients in the upper TSH tertile.

CONCLUSION

In patients with CAD undergoing PCI, TSH level in the upper part of reference range was associated with increased risk of mortality after PCI.

Exercise induced hypercoagulability, increased von Willebrand factor and decreased thyroid hormone concentrations in sled dogs

Background

Sled dogs performing endurance races have been reported to have a high incidence of gastric erosions or ulcerations and an increased risk of gastro intestinal bleeding leading to death in some cases. In addition, these dogs also become hypothyroid during training and exercise. Canine hypothyroidism has been shown to correlate with decreased von Willebrand factor antigen and potentially increased bleeding tendency. Whether increased gastro intestinal bleeding risk is exacerbated due to changes in the hemostatic balance is unknown. The aim of this study was to investigate the hemostatic balance in sled dogs before and after exercise and in addition evaluate any correlation to thyroid status. Twenty sled dogs have been assessed in untrained and trained condition and immediately after exercise. The first sample was collected in the autumn following a resting period, and subsequently the dogs were exposed to increased intensity of training. After four months the peak of physical condition was reached and a 68 km long sled pulling exercise was performed. Samples were collected before and immediately after the exercise. Evaluated parameters were: plasma thromboelastographic (TEG) R, SP, α and MA, activated partial thromboplastin time (aPTT), prothrombin time (PT), fibrinogen, von Willebrand factor (vWf), D-dimer, platelet number, thyroid hormones, hematocrit and C-reactive protein (CRP).

Results

Exercise induced an overall hypercoagulable state characterized by significant decreases of TEG R and SP and an increase of α, increased concentrations of plasma vWf and decreased aPTT. In addition, a proinflammatory status was seen by a significant increase of serum CRP concentrations. Thyroid status was confirmed to be hypothyroid as training and exercise induced significant decrease of thyroxin (T4), free thyroxin (fT4) and thyroxin stimulating hormone (TSH) concentrations. Fibrinogen decreased significantly and PT increased. The training-induced changes showed correlation between T4, fT4 and aPTT and correlation between TSH and fibrinogen. Exercise-induced changes showed correlation between T4 and PT.

Conclusions

Exercise was associated with a hypercoagulable state and an increase of vWf concentration in this group of sled dogs. Decreased thyroid hormone concentrations after training and exercise were confirmed, but were associated with increased and not decreased vWf in this group of sled dogs.

Congenital hypothyroidism - An usual suspect at an unusual age: A case series

Menorrhagia is the most common menstrual irregularity in hypothyroid women. However, it is an uncommon presentation of congenital hypothyroidism (CH). In the era of newborn screening across the world, when CH is extremely rare, we came across four cases of CH due to delayed diagnosis, presenting in adulthood with severe menorrhagia.

Hemostatic changes in thyroid diseases

Several studies have reported hemostatic abnormalities, both in terms of bleeding or thrombosis, in patients with various thyroid dysfunctions. The aim of this review is to briefly discuss the relationship between thyroid disorders and hemostasis (i.e. primary hemostasis, coagulation factors and fibrinolytic system). From the analysis of the more recent literature data, it appears evident that most of the coagulation abnormalities associated with thyroid disorders are a consequence of a direct action of thyroid hormones on the synthesis of various hemostatic factors or a derangement of immune function. On the whole, these data suggest that a hypercoagulable state is present in hyperthyroid patients, while patients suffering from moderate hypothyroidism are at increased risk of thrombosis contrasting with the bleeding tendency of those presenting severe hypothyroidism.

A literature review on the adverse effects of hypothyroidism on kidney function

Thyroid produce two important hormone of thyroxine or tetraidothyronine (T4) and triidothyronine (T3), which are involved in whole aspect of metabolism. T4 and T3 play vital role in all biochemical function, growth and development in human body. The basic metabolic pathways in kidney and every organ in human controlled by these hormones. T4 and T3 are involved in kidney function in health and diseases condition therefore the pathophysiology of kidney can be directly influenced and regulated by thyroid hormones. Kidney growth, haemodynamic, blood circulation, tubular, electrolyte balance and glomerular filtration rate (GFR) are among such crucial process. Hypothyroidism which accompanied with reduced thyroid hormone production adversely affect the renal functions, development and eventually leading to reduced weight, kidney vascular disorders, electrolyte, tubular transport imbalances, lower filtration rate and other adverse consequences of hypothyroidism. On other hand kidney diseases can also disrupt the thyroid function metabolism resulting in the subsequent hypothyroidism. It is an interesting subject in how thyroid and kidney in health and diseases closely interacted. For the ideal clinical follow up of either of thyroid and renal diseases the two organs should be simultaneously examined for a proper patient management. Close correlation of thyroid and kidney clinical teams are essential to check the cross reactions and adverse interactions which might be produced between these two vital organs to avoid misdiagnosis either of thyroid or kidney abnormalities.

Myxedema coma: a new look into an old crisis

Myxedema crisis is a severe life threatening form of decompensated hypothyroidism which is associated with a high mortality rate. Infections and discontinuation of thyroid supplements are the major precipitating factors while hypothermia may not play a major role in tropical countries. Low intracellular T3 leads to cardiogenic shock, respiratory depression, hypothermia and coma. Patients are identified on the basis of a low index of suspicion with a careful history and examination focused on features of hypothyroidism and precipitating factors. Arrythmias and coagulation disorders are increasingly being identified in myxedema crisis. Thyroid replacement should be initiated as early as possible with careful attention to hypotension, fluid replacement and steroid replacement in an intensive care facility. Studies have shown that replacement of thyroid hormone through ryles tube with a loading dose and maintenance therapy is as efficacious as intravenous therapy. In many countries T3 is not available and oral therapy with T4 can be used effectively without major significant difference in outcomes. Hypotension, bradycardia at presentation, need for mechanical ventilation, hypothermia unresponsive to treatment, sepsis, intake of sedative drugs, lower GCS and high APACHE II scores and Sequential Organ Failure Assessment (SOFA) scores more than 6 are significant predictors of mortality in myxedema crisis. Early intervention in hypothyroid patients developing sepsis and other precipitating factors and ensuring continued intake of thyroid supplements may prevent mortality and morbidity associated with myxedema crisis.

Can subclinical hypothyroidism explain some sudden deaths due to pulmonary embolism without evident risk factors?

Thyroid pathology is rarely involved in the pathogenesis of sudden death in young people, and usually, when this is the case, is associated with acute changes of thyroid hormone blood levels. Three main thyroid causes of sudden death are known and used in tanathologic chains: thyrotoxicosis, myxedematous coma and, as of recently, lymphocytic thyroid infiltration. Coagulation disorders associated with thyroid disease are usually mild and not associated with sudden death. There are some studies showing an increased risk for unprovoked deep venous thrombosis in patients with hypothyroidism but there is none, to our knowledge, showing a correlation between hypothyroidism, deep venous thrombosis and sudden death. Our article suggests that subclinical hypothyroidism can lead to coagulation disorders and deep venous thrombosis which can explain some cases of sudden death associated with pulmonary embolism without other significant risk factors.

Thrombin-Activatable Fibrinolysis Inhibitor (TAFI) Antigen and Activity Assay in Patients With Primary Hypothyroidism

Hypothyroidism causes a tendency for cardiovascular diseases. It was recently shown that thrombin-activatable fibrinolysis inhibitor (TAFI) attenuates fibrinolysis and also fibrin-plasminogen interaction by the removal of lysine and arginine residues from fibrin monomers. The aim of this study was to determine the effects of overt hypothyroidism on the levels of TAFI antigen (TAFI Ag) and TAFI activity (TAFIa). Thirty-one overt primary hypothyroid patients and age- and gender-matched 25 healthy controls were enrolled in the study. Patients were treated with L-thyroxine after the collection of blood samples. Thyroid functions were reevaluated following the achievement of euthyroid status. Thrombin-activatable fibrinolysis inhibitor Ag, tissue plasminogen activator (t-PA), and plasminogen activator inhibitor 1 (PAI-1) levels were measured with the enzyme-linked immunosorbent assay (ELISA). Thrombin-activatable fibrinolysis inhibitor activity was assessed with the chromogenic assay. Thrombin-activatable fibrinolysis inhibitor Ag (1.63% ± 0.42% vs 1.32% ± 0.36%, P < .01) and TAFIa (14.2 ± 4.12 vs 11.6 ± 3.49 μg/mL, P < .05) levels were elevated in hypothyroid patient compared to controls. Plasminogen activator inhibitor 1 and t-PA levels were not significantly different between both groups. In hypothyroid patients, TAFI Ag levels were correlated with free T4 (r = -.373, P < .05) and thyroid-stimulating hormone (TSH) levels (r = .748, P < .001). Regression analysis showed that TSH levels were predictors of TAFI Ag levels (P < .001, β =.671, 95% confidence interval [CI]: 0.008-0.017). Following L-thyroxine treatment, TAFI Ag (1.63% ± 0.42%, 1.34% ± 0.33%, P < .05) and TAFIa (14.2 ± 4.12 μg/mL, 12.0 ± 2.77 μg/mL, P < .05) levels were significantly decreased, but t-PA and PAI-1 levels remained unchanged. This results point out that the fibrinolytic activity was decreased in hypothyroid patients, and therefore the achievement of euthyroid status is important in ameliorating the increased risk of cardiovascular disease.

Levothyroxine (LT4) suppression treatment for benign thyroid nodules alters coagulation

OBJECTIVE

Endogenous hyperthyroidism is associated with altered coagulation. The aim of the present study is to investigate the effect of levothyroxine (LT(4)) suppression treatment for benign thyroid nodules on coagulation system.

DESIGN

Prospective case-control study. Patients Thirty consecutive euthyroid pre-menopausal women with nodular goitre disease and 28 healthy controls were included in the study.

MEASUREMENTS

Plasma fibrinogen, d-dimer, von Willebrand factor (vWF), tissue factor (TF), tissue plasminogen activator (tPA), plasminogen activator inhibitor (PAI-1) and tissue factor pathway inhibitor (TFPI) levels were measured at baseline and after LT(4) suppression therapy.

RESULTS

Plasma levels of fibrinogen, d-dimer, vWF, TF and PAI-1 increased significantly after treatment with LT(4) for 1 year. Serum FT(4) was a significant predictor of increased fibrinogen, vWF and PAI-1 levels, when the data was controlled for age and BMI.

CONCLUSIONS

Our results suggest that LT(4) suppression therapy for benign thyroid nodules is associated with enhanced coagulation.

Venous Thromboembolism in Patients Hospitalized With Thyroid Dysfunction

The objective of this investigation is to explore a possible role of thyroid dysfunction in venous thromboembolism (VTE). The number of patients discharged from short-stay nonfederal hospitals in the United States, from 1979 to 2005, with a diagnostic code for hypothyroidism or hyperthyroidism, pulmonary embolism (PE), and deep venous thrombosis (DVT) was obtained from the National Hospital Discharge Survey (NHDS). Among 19 519 000 hospitalized patients discharged with a diagnosis of hypothyroidism from 1979 to 2005, 119 000 (0.61%) had PE. Among patients with no thyroid dysfunction, PE was diagnosed in 3 372 000 of 908 805 000 patients (0.37%; relative risk = 1.64, 95% CI 1.63-1.65). Deep venous thrombosis was diagnosed in 1.36% of hypothyroid patients and in 0.84% of patients with no thyroid dysfunction (relative risk = 1.62, 95% CI 1.61-1.62). The relative risk of PE in patients with hypothyroidism was highest in patients <40 years of age (relative risk = 3.99) and the relative risk of DVT was also highest in patients <40 years (relative risk = 2.25). Hyperthyroidism was not associated with an increased risk of VTE (relative risk = 0.98, 95% CI = 0.96-1.01). In conclusion, an increased risk of PE, DVT, and VTE was shown in patients with hypothyroidism but not hyperthyroidism. Antithrombotic prophylaxis in patients with severe hypothyroidism, however, should be viewed with caution because of a possible hyperfibrinolytic state in such patients.

Hypothyroidism and acquired von Willebrand's syndrome: a systematic review

Acquired von Willebrand's syndrome type I is the supposed main underlying cause of bleeding tendency in hypothyroid patients. The purpose of this systematic review was to summarize the published evidence on the association between hypothyroidism and acquired von Willebrand's syndrome. All published clinical epidemiological and interventional studies, case reports and in vitro studies that investigated the association between hypothyroidism and acquired von Willebrand's syndrome were identified by a computer-assisted search of the MEDLINE and EMBASE electronic databases. A quality assessment was performed for clinical epidemiological studies. A total of 41 papers were included. A total of 22 epidemiological in vivo studies, two in vitro studies and 47 case reports were finally analyzed. No high quality in vivo study was identified. Almost all bleeding episodes described in the case reports were mucocutaneous. von Willebrand factor (VWF) antigen value was available for 23 patients: median value 28 U/dL (range: 4-45); VWF activity was available for 24 patients: median value 28.5 U/dL (range: <3-55); factor VIII activity was available for 16 patients: median value 47 U/dL (range: 9-74). Acquired von Willebrand's syndrome may be the main factor responsible for bleeding diathesis in overt hypothyroid patients. Even if bleeding episodes are mainly mild and mucocutaneous, blood transfusion, drug administration or surgical procedure may be required.

Thrombin activatable fibrinolysis inhibitor antigen levels are inversely correlated with plasminogen activator inhibitor-1 antigen levels in hyperthyroid patients

Both increased and decreased fibrinolytic activity have been reported in patients with hyperthyroidism. Elevated levels of plasma plasminogen activator inhibitor-1 (PAI-1) antigen have been found in hyperthyroid patients. Thrombin activatable fibrinolysis inhibitor (TAFI) is a novel plasma protein, which inhibits fibrinolysis through removal of C-terminal lysines from partially degraded fibrin. Previously, we showed that plasma TAFI antigen levels were increased in patients with overt and subclinical hypothyroidism. The aim of this study is to investigate plasma levels of TAFI and PAI-1 antigens in hyperthyroid patients. PAI-1 and TAFI antigen levels were measured in the plasma of 29 patients with hyperthyroidism (14 overt hyperthyroid and 15 subclinical hyperthyroid), and 26 healthy individuals. Although there were increased levels of PAI-1 antigen in hyperthyroid patients, plasma TAFI antigen levels were significantly lower compared to controls (80.79 ng/ml vs. 32.42 ng/ml, p = 0.000 for PAI-1; 10.42 microg/ml vs. 12.24 microg/ml, p = 0.009 for TAFI). Elevated PAI-1 antigen levels were positively correlated with free thyroid hormones, although TAFI antigen levels were in negative correlation with free thyroxine. Furthermore, an inverse correlation between PAI-1 and TAFI antigen levels was found. Our study demonstrated that TAFI antigen levels were decreased in patients with hyperthyroidism. Inverse correlation with PAI-1 suggests that the decrease in TAFI antigen levels may be due to activation of TAFI pathway. Further studies evaluating the underlying mechanisms of low TAFI antigen levels in hyperthyroidism should be undertaken.

The coagulation system in endocrine disorders: a narrative review

Endocrine disorders can influence the haemostatic balance. Abnormal coagulation test results have been observed in patients with abnormal hormone levels. Also unprovoked bleeding or thrombotic events have been associated with endocrine disease. The aim of the present review is to summarise the available evidence on the influence of common endocrine disorders on the coagulation system, and their possible clinical implications. We focus on thyroid dysfunction, hyper- and hypocortisolism and growth hormone disturbances, while other endocrine disorders are only briefly discussed. In the published literature a clear bleeding diathesis has only been associated with overt hypothyroidism, mainly mediated by an acquired von Willebrand syndrome. A clinically relevant hypercoagulable state may be present in patients with hyperthyroidism, hypercortisolism or abnormal growth hormone levels, but adequate prospective clinical studies are lacking. Also effects of pheochromocytoma, hyperprolactinaemia and hyperaldosteronism on the coagulation system have been described. It is apparent that unprovoked bleeding and thrombotic episodes can be secondary to endocrine disorders.

Elevated thrombin activatable fibrinolysis inhibitor (TAFI) antigen levels in overt and subclinical hypothyroid patients were reduced by levothyroxine replacement

The influence of hypothyroidism on haemostasis is an active research area. Not only bleeding tendency but also hypercoagulable states have been reported in hypothyroid patients. Decreased and increased fibrinolytic activity in hypothyroid patients has been shown in several studies. Thrombin activatable fibrinolysis inhibitor (TAFI) is an inhibitor of fibrinolysis, which has been recently isolated from human plasma. The aim of our study was to determine plasma TAFI antigen levels in overt and subclinical hypothyroidism, and to investigate the effect of levothyroxine treatment on TAFI levels. The study was performed in age- and sex-matched 30 overt hypothyroid, 30 subclinical hypothyroid patients, and 30 healthy controls. Blood samples were obtained from patients with overt and subclinical hypothyroidism before levothyroxine replacement, and one month after achieving a euthyroid state with levothyroxine. TAFI antigen levels were measured using Enzyme-Linked ImmunoSorbent Assay kits (Affinity Biologicals; Ontario, Canada). In baseline evaluation both the overt and subclinical hypothyroid groups had higher TAFI antigen levels than control group (p<0.05). High levels of TAFI antigen were correlated with the degree of thyroid failure. After achieving euthyroid state with levothyroxine replacement, TAFI antigen levels decreased significantly in patients with overt and subclinical hypothyroidism (p<0.05). Our data suggest that there are elevated plasma levels of TAFI antigen both in overt and subclinical hypothyroidism, which may be associated with hypofibrinolysis and elevated risk of thrombosis. Normalization of thyroid state by levothyroxine replacement seems to be effective in lowering of TAFI antigen levels in hypothyroidism.

Investigation of tissue factor and other hemostatic profiles in experimental hypothyroidism

The influence of thyroid failure on hemostasis has been studied and is still not well understood. These patients have high risk for cardiovascular diseases because of the lipid metabolism and procoagulant agents. But the influence of thyroid failure on hemostasis is controversial. Tissue factor (TF) has an important role in the thromboembolic state. Recent experiments have demonstrated that TF-dependent activation of the coagulation cascade plays an important role in the pathophysiology of intravascular thrombus formation. The purpose of the present study was to investigate the contributions of TF, factor VII:C (FVII:C), factor XII:C (FXII:C), and fibrinogen in experimental hypothyroidism. TF was obtained from the thyroid gland and lung tissue of 10 rats following experimental hypothyroidism induced for 30 d and compared with similar tissue from 10 control rats. Significantly increased TF activities were found in hypothyroid rats. By contrast, FVII:C level was significantly decreased when compared with the control group. In this respect it is interesting to note that a hypercoagulable state due to increased thromboplastic activity may occur. Based on those results, elevated tissue factor activities (TFa) of the patients with low thyroid dysfunction may have another risk factor for cardiovascular diseases.

Impact of short-term hypothyroidism on systemic anticoagulation in patients with thyroid cancer and coumarin therapy

Unlike hyperthyroidism, few data exist regarding the impact of hypothyroidism on systemic anticoagulation with coumarin derivates. Therefore, we evaluated a potential impact of short-term hypothyroid conditions on systemic anticoagulation with coumarin derivates in patients after complete thyroidectomy for treatment of thyroid cancer. Fifteen patients with differentiated thyroid cancers and continued international normalized ratio (INR)-adjusted therapy with coumarin derivates were included in this retrospective analysis. A total of 88 laboratory tests was analyzed. INR values were compared between thyroid-stimulating hormone (TSH) values greater than 10 and 10 mU/L or less. An INR value of less than 2.0 was defined as being out of the therapeutic range. Analysis of significant differences between categorized TSH and INR values were performed by using X(2) analysis, correlation of continuous TSH and INR values by using the Pearson's analysis. When TSH was greater than 10 mU/L (n = 50) the INR value was less than 2.0 in 76.0% (n = 38) cases. In contrast, the INR value was less than 2.0 in only 21.1% (n = 8; p < 0.0001) of patients with TSH of 10 mU/L or less (n = 38). Correlation between continuous TSH and INR values was r = -0.589 (p < 0.0001). Based on the results of the present study, it seems to be necessary to monitor the anticoagulation parameters more often in patients with hypothyroidism and either to correct the hypothyroid state, or in cases of desired hypothyroid conditions, to adjust the therapy with coumarin derivates in order to ensure a sufficient anticoagulation.

Does Treating Subclinical Hypothyroidism Improve Markers of Cardiovascular Risk?

Subclinical hypothyroidism is defined as an elevated serum thyroid-stimulating hormone (TSH) level in the face of normal free thyroid hormone values. The overall prevalence of subclinical hypothyroidism is 4-10% in the general population and up to 20% in women aged >60 years. The potential benefits and risks of therapy for subclinical hypothyroidism have been debated for 2 decades, and a consensus is still lacking. Besides avoiding the progression to overt hypothyroidism, the decision to treat patients with subclinical hypothyroidism relies mainly on the risk of metabolic and cardiovascular alterations. Subclinical hypothyroidism causes changes in cardiovascular function similar to, but less marked than, those occurring in patients with overt hypothyroidism. Diastolic dysfunction both at rest and upon effort is the most consistent cardiac abnormality in patients with subclinical hypothyroidism, and also in those with slightly elevated TSH levels (>6 mIU/L). Moreover, mild thyroid failure may increase diastolic blood pressure as a result of increased systemic vascular resistance. Restoration of euthyroidism by levothyroxine replacement is generally able to improve all these abnormalities. Early clinical and autopsy studies had suggested an association between subclinical hypothyroidism and coronary heart disease, which has been subsequently confirmed by some, but not all, large cross-sectional and prospective studies. Altered coagulation parameters, elevated lipoprotein (a) levels, and low-grade chronic inflammation are regarded to coalesce with the hypercholesterolemia of untreated patients with subclinical hypothyroidism to enhance the ischemic cardiovascular risk. Although a consensus is still lacking, the strongest evidence for a beneficial effect of levothyroxine replacement on markers of cardiovascular risk is the substantial demonstration that restoration of euthyroidism can lower both total and low-density lipoprotein-cholesterol levels in most patients with subclinical hypothyroidism. However, the actual effectiveness of thyroid hormone substitution in reducing the risk of cardiovascular events remains to be elucidated. In conclusion, the multiplicity and the possible reversibility of subclinical hypothyroidism-associated cardiovascular abnormalities suggest that the decision to treat a patient should depend on the presence of risk factors, rather than on a TSH threshold. On the other hand, levothyroxine replacement therapy can always be discontinued if there is no apparent benefit. Levothyroxine replacement therapy is usually safe providing that excessive administration is avoided by monitoring serum TSH levels. However, the possibility that restoring euthyroidism may be harmful in the oldest of the elderly population of hypothyroid patients has been recently raised, and should be taken into account in making the decision to treat patients with subclinical hypothyroidism who are aged >85 years.

Thyroid diseases and cerebrovascular disease

BACKGROUND AND PURPOSE

Acute cerebral ischemia has been described in different diseases of the thyroid gland, and not only as a result of thyrotoxic atrial fibrillation and cardioembolic stroke. The purpose of this review is to summarize the studies on the relationship between thyroid diseases and cerebrovascular diseases, discussing the main findings for overt hyperthyroidism and hypothyroidism, as well as for subclinical thyroid dysfunction.

SUMMARY OF REVIEW

In overt hyperthyroidism, cardioembolic stroke is clearly associated to thyrotoxic atrial fibrillation, and in subclinical hyperthyroidism with serum thyroid-stimulating hormone levels <0.1 mU/L, the incidence of atrial fibrillation is increased. Although in vitro and in vivo studies indicate a hypercoagulability state in hyperthyroidism, there is insufficient evidence to prove that this state leads to an increased risk of cardiac emboli. However, the hypothesis that overt hyperthyroidism may cause acute cerebral venous thrombosis is intriguing. Possible associations between hyperthyroidism and Moyamoya or Giant cell arteritis have only been described in case reports. There is enough evidence that overt hypothyroidism is associated with several traditional and newer atherosclerotic risk factors, especially hypertension, hyperlipidemia, and hyperhomocysteinemia. For subclinical hypothyroidism, these associations are less certain. Hypothyroidism has been associated with signs of aortic or coronary atherosclerosis, but no case-control or cohort studies have ever investigated hypothyroidism as a possible risk factor for atherothrombotic stroke.

CONCLUSIONS

Hyperthyroidism is associated with atrial fibrillation and cardioembolic stroke. Hypothyroidism is associated with a worse cardiovascular risk factor profile and leads to progression of atherosclerosis. Associations between hyperthyroidism and acute cerebral venous thrombosis, Moyamoya, and Giant cell arteritis have been suggested, but sound evidence is lacking. Additional studies are needed to clarify these issues.

Global fibrinolytic capacity in patients with subclinical hypothyroidism

Subclinical hypothyroidism (SH) represents the earliest stages of hypothyroidism but the benefits of detecting and treating SH are not well known. The aim of this study was to evaluate the alterations in global fibrinolytic capacity (GFC), which indicates the overall fibrinolytic activity, in patients with SH. The study group comprised of 15 patients with SH and 15 healthy controls. The GFC was significantly lower in patients with SH than in control group (p<0.002). This result suggests a relative hypercoagulable state in SH.

Effect of levothyroxine replacement therapy on coagulation and fibrinolysis in severe hypothyroidism

OBJECTIVE

We previously demonstrated that patients suffering from moderate hypothyroidism were at increased risk of thrombosis contrasting with the bleeding tendency of those presenting severe hypothyroidism. The latter state is associated with hemostatic anomalies including von Willebrand type 1 disease and increased fibrinolytic capacity. With the exception of von Willebrand type 1 disease, reversibility of hemostatic changes is not established after levothyroxine replacement therapy. Therefore our objective was to analyze the reversibility of these anomalies.

MATERIALS AND METHODS

We analyzed the impact of levothyroxine treatment on lipid parameters, fibrinogen, platelet count, D-dimers, alpha2 antiplasmin activity, plasminogen activity, tissue plasminogen activator antigen (t-PA Ag), plasminogen activator inhibitor type 1 antigen (PAI-1 Ag) and coagulation factors (factor VIII coagulant, von Willebrand factor antigen, von Willebrand factor and factor IX) in 23 patients with severe hypothyroidism (TSH level > 50 mU/ I).

RESULTS

Mean fibrinogen levels increased by 14.2% while t-PA Ag and PAI-1 Ag increased by 42.6 and 69%, respectively, after correction of hypothyroidism. Interestingly, post-treatment PAI-1 Ag levels tended to be higher in patients with normal-high final TSH levels than in patients with normal-low final TSH levels. Our results suggest that normalization of fibrinolysis is obtained after a transient decrease of fibrinolytic activity. We also confirmed the correction of coagulation factor abnormalities upon levothyroxine replacement therapy.

CONCLUSIONS

We demonstrated that the coagulation disorders and the hyperfibrinolytic status of severe hypothyroid patients were corrected upon levothyroxine therapy. However, the clinical consequences of the transient decrease of the fibrinolytic activity during the course of TSH normalization need further studies.

Effects of levothyroxine treatment on biochemical and hemostasis parameters in patients with hypothyroidism

OBJECTIVE

The aims of the study were to evaluate the disturbances in the coagulation system in patients with overt hypothyroidism (OH), to assess the effects of levothyroxine (LT4) on the coagulation parameters, and to determine whether subclinical hypothyroidism (SH) affects concentrations of coagulation markers and several biochemical parameters, thereby supporting early substitution.

DESIGN

The study included 15 patients with SH (TSH levels 5-10 mU/l), 15 patients with OH and 15 euthyroid controls.

METHODS

Blood urea nitrogen, creatinine, creatine phosphokinase, aspartate aminotransferase, lactate dehydrogenase, total-cholesterol, high density lipoprotein-cholesterol, low density lipoprotein-cholesterol and triglyceride levels, and bleeding time, prothrombin time (PT), activated partial thromboplastin time (APTT), factor VIII activity, von Willebrand factor activity (vWF), platelet count and clotting time were evaluated just before and three months after the maintenance of euthyroidism with LT4 treatment.

RESULTS

Factor VIII and vWF activities were lower in patients with SH than in controls (P < 0.01). Increased bleeding time, PT, APTT and clotting time and decreased factor VIII activity and vWF activity were observed in patients with OH when compared with controls. Bleeding time, PT, APTT and clotting time decreased and factor VIII activity, vWF and platelet count increased after LT4 in patients with OH. Increases in factor VIII activity and vWF (P < 0.01) were detected also in the SH group with treatment.

CONCLUSIONS

OH is associated with significant abnormalities in clotting parameters which are reversed by LT4. In contrast, SH is associated with minor changes in factor VIII activity and vWF which are reversible by LT4. Serum lipids and other measured parameters are not improved by LT4 in patients with TSH < 10 mU/l and these data fail to demonstrate a need to treat such patients.

Thyroid, hemostasis and thrombosis

The aim of this paper is to briefly review some practical aspects of the relationship between thyroid function and several disorders of the hemostatic system in terms of bleeding and thrombosis. Thrombocytopenia, acquired hemophilia, hypercoagulability, cardioembolism and other biochemical coagulative and fibrinolytic abnormalities have been described in the past years both in hyper- and hypothyroidism. Since most of hyper- and hypothyroid conditions are the consequence of autoimmune thyroid disease (1), either deranged immune function, altered circulating thyroid hormone concentration, or both may concur in the pathogenesis of hemostatic disorders of potential crucial clinical impact. These aspects will be outlined and discussed in an attempt to give answers to some questions, often arising in the clinical approach.

Hemostasis and thyroid diseases revisited

Several papers have reported various hemostatic abnormalities in patients with thyroid diseases. In this concise review, the traditional associations between hypercoagulable state and hyperthyroidism and between hypocoagulative state and hypothyroidism are critically revised on the basis of more recent literature data. In particular, we analyze the hemostatic balance (primary hemostasis, coagulation factors and fibrinolytic system) in different thyroid disorders. Although most of the studies published so far include limited numbers of patients and their results are sometimes contradictory, we can conclude that hyperthyroidism is generally accompanied by a hypercoagulable state, whereas the hemostatic profile in hypothyroidism and thyroid cancer depends on the severity of the disease.

Plasma levels of free tissue factor pathway inhibitor in patients with various thyroid disorders

Various coagulation abnormalities occur in thyroid disorders and its range may vary from subclinical laboratory abnormalities to clinically significant disorders of coagulation. Tissue factor pathway inhibitor (TFPI), which inhibits the initial reaction of tissue factor mediated coagulation pathway, is reported to be increased in patients with Graves disease (GD) in one study. Hyperthyroid (n=10), hypothyroid (n=10) and subclinical hypothyroid (n=10) patients and control cases (n=16) were evaluated for free and total tissue factor pathway inhibitor (tTFPI), plasminogen activator inhibitor-1 (PAI-1) and tissue plasminogen activator (tPA) levels in disease and euthyroid states. Free TFPI levels were significantly higher in hyperthyroid patients compared with the control group and subclinic hypothyroid patients (p<0.001), but not with hypothyroid patients (p>0.05). After the euthyroid state was obtained in the hyperthyroid group, the levels of total TFPI (p<0.05), free TFPI (fTFPI) (p<0.005), t-PA (p<0.005) and PAI-1 (p<0.02) decreased significantly. In hyperthyroid patients, there was a strong correlation between thyroid functions and free TFPI levels. In conclusion, we hypothesize that coagulation abnormalities seen in thyroid disorders cannot be explained directly with the impaired fibrinolytic activity but also with the elevated fTFPI levels. Both increased plasma fTFPI and PAI-1 levels could be markers of the peripheral activity of thyroid hormones.

Hemostatic system as a risk factor for cardiovascular disease in women with subclinical hypothyroidism

Hypothyroidism has been associated with atherosclerosis. The mechanisms of atherosclerosis in patients with thyroid failure remain controversial. Hypofibrinolysis might be a risk factor for thromboembolic disease in subclinical hypothyroidism (SH). We measured fibrinolytic activity in patients with SH before and after levothyroxine (LT(4)) treatment and compared it to those of controls. We prospectively included 35 patients with SH and 30 healthy controls. We treated patients with LT(4) until almost 6 months after the euthyroid state has been achieved. We measured fibrinogen, D-dimer, antithrombin III (ATIII), plasminogen activator inhibitor-1 (PAI-1), tissue plasminogen activator (tPA) activity, and factor VII. Clinical and anthropometric variables were recorded for both groups. We found increased levels of fibrinogen, PAI-1, and factor VII and decreased levels of ATIII activity in patients compared to control (p < 0.001 and p < 0.05). Decrease of tPA was not significant (p > 0.05). At the end of the LT(4) treatment, significant decreases were determined in PAI-1 and factor VII (p < 0.05). In conclusion, our data suggest an important role of hypofibrinolytic and hypercoagulable state on the development of atherosclerosis in patients with SH and beneficial effects of LT(4 )treatment for decreasing the risk of atherosclerosis.

Efficacy of desmopressin as surgical prophylaxis in patients with acquired von Willebrand disease undergoing thyroid surgery

Coagulation abnormalities may occur in patients with thyroid diseases. We report on 14 patients undergoing thyroid surgery for a thyroid disease with an alteration of coagulation parameters resembling von Willebrand disease. Subcutaneous desmopressin was first tested and then used successfully in these patients as surgical prophylaxis, with no side-effects or bleeding complications during or after surgery. This study highlights the need for coagulation studies in patients with thyroid diseases undergoing thyroid surgery. Subcutaneous desmopressin may be used in these patients in order to prevent a surgically related bleeding risk.

Haemostatic profile in hypothyroidism as potential risk factor for vascular or thrombotic disease

The influence of thyroid failure on haemostasis is controversial, both hypocoagulable and hypercoagulable states have been reported. Since both subclinical and overt hypothyroidism have been associated with atherosclerosis, a hypercoagulable state in addition might represent a risk factor for thromboembolic disease. We investigated various haemostatic variables in 42 women with subclinical hypothyroidism and compared them to 66 euthyroid controls. Prothrombin time, activated partial thromboplastin time, fibrinogen, factor VII activity (FVII:C), factor VII antigen (FVII:Ag), factor VIII activity, von Willebrand factor (vWF), antithrombin III, heparin cofactor II, protein C, protein S, plasminogen, antiplasmin, plasminogen activator inhibitor and tissue plasminogen activator, as well as common lipid variables, were measured. Factor VII:C (P < 0.02) and the ratio FVII:C/FVII:Ag (P < 0.01) were significantly increased in subclinical hypothyroid patients compared to the control group. Both parameters remained higher in hypothyroid patients after exclusion of 18 women on oestrogen replacement therapy. No differences were found between the groups with respect to vWF or the other haemostatic and lipid variables tested. Patients with subclinical hypothyroidism had significantly higher levels of FVII:C. The greater increase in FVII:C compared to that of FVII:Ag, as shown by the increase in their ratio, might reflect the presence of activated FVIIa. This might mean a hypercoagulable state, which could contribute to the increased prevalence of coronary heart disease reported in such patients. A hypercoagulable state might be another argument in favour of thyroxine replacement treatment in subclinical hypothyroidism, especially in patients with additional risk factors for vascular disease.

[Hemorrhage complicating heparin treatment in a patient with myxedema]

A 75 year-old woman was admitted for a myxoedematous coma. Treatment included a prophylactic administration of low molecular weight heparin. During recovery from coma she experienced pain in her right calf. The anticoagulant therapy was switched to subcutaneous calcium heparin. However, the latter had to be discontinued due to the formation of a haematoma of a thigh. Clinical and biological data were in favour of a mechanism of heparin stocking during coma followed by its release during recovery.

Acquired von Willebrand's syndrome causing a hemorrhagic diathesis in a patient with hypothyroidism

The occurrence of bleeding diathesis with menorrhagia and easy bruising may occur in patients with moderate to severe hypothyroidism sometimes linked to acquired von Willebrand's disease (VWD). We describe a patient with profound hypothyroidism in whom the diagnosis of hypothyroidism was established while evaluating uncontrolled gingival bleeding after a dental procedure. Thyroid hormone replacement led to a rise in von Willebrand factor, factor VIIIC, and a significant fall in the elevated bleeding time from 15 to 8 min. Acquired von Willebrand's disease is an unusual manifestation of hypothyroidism and is reversible.

Primary haemostasis in thyroid disease

OBJECTIVES

There have been reports on a bleeding tendency in hypothyroidism resembling von Willebrand's disease. The aim of the present study was to investigate whether altered primary haemostasis is a general phenomenon in thyroid disease.

DESIGN/SETTING

A total of 10 patients with hyperthyroidism and nine patients with hypothyroidism were studied at diagnosis, and during treatment with carbimazole or L-thyroxine, respectively, when euthyroidism had been achieved.

RESULTS

In untreated hypothyroidism, template bleeding time was prolonged (median 9.3 min, range 3.8-20.0 min) compared to that in controls (median 4.0 min, range 3.0-6.0 min; P < 0.05), whereas maximal agglutination velocity induced by ristocetin was decreased (38% min-1, range 4-52% min-1 vs. 70% min-1, range 60-81% min-1, P < 0.05). The level of von Willebrand factor antigen in plasma from hypothyroid patients was less than half of the value in hyperthyroid patients. This difference disappeared after euthyroidism was achieved.

CONCLUSIONS

We found that changed primary haemostasis is a general feature of hypothyroidism, and that it is resolved after levothyroxine treatment.

Effect of acute desmopressin and of long-term thyroxine replacement on haemostasis in hypothyroidism

OBJECTIVE

Hypothyroidism can be complicated by bleeding symptoms such as easy bruising, menorrhagia and sometimes even a severe bleeding tendency with fatal outcome. Usually there is a prolonged bleeding time, or a low plasma concentration of coagulation factor VIII (FVIII) or von Willebrand factor (vWF). The aim of the present study was to investigate the acute haemostatic effect of desmopressin in hypothyroid patients. Another aim was to study the long-term effect of thyroxine replacement on the plasma concentrations of coagulation factors and to ascertain the duration of thyroxine treatment needed to restore haemostatic function.

DESIGN AND PATIENTS

The effects of desmopressin, given intravenously over 10 minutes at a dosage of 0.3 micrograms/kg, and thyroxine treatment on haemostatic function were studied prospectively in 10 patients with hypothyroidism.

RESULTS

Before treatment only five of the patients manifested bleeding symptoms; one had prolonged bleeding time, and one had low plasma concentrations of vWF:Ag. Desmopressin virtually immediately reduced bleeding time, enhanced platelet adhesiveness, and significantly increased plasma concentrations of FVIII and vWF. The plasma concentrations of FVIII and vWF showed a significant increase after 4 months, whereas 7 months treatment with thyroxine was needed to reduce bleeding time significantly.

CONCLUSION

Our results suggest that in hypothyroid patients desmopressin may be of value for the acute treatment of bleeding or as cover for surgery.

Hypothyroidism: a comprehensive review

Hypothyroidism is a common clinical entity encountered frequently in most adult primary care settings. The reported prevalence in the general population is approximately 3% in men, but as high as 10% in women (Sawin, Geller, Hershman, Castelli, & Bacharach, 1989). The disease process affects every major organ system, contributing to a broad range of symptoms. Clinicians need to be familiar with the signs, the symptoms, and the appropriate laboratory studies, so that timely and accurate diagnoses can be made. This article reviews normal thyroid physiology and thyroid pathophysiology, as well as the diagnosis and treatment of several important clinical entities resulting in hypothyroidism. Research findings are included insofar as they relate to current clinical practice.