Methimazole: an alternative route of administration

Endocrine Care for the Surgical Patient: Diabetes Mellitus, Thyroid and Adrenal Conditions

Patients with hyperglycemia, thyroid dysfunction, and adrenal insufficiency face increased perioperative risk, which may be mitigated by appropriate management. This review addresses preoperative glycemic control, makes evidence-based recommendations for the increasingly complex perioperative management of noninsulin diabetes medications, and provides guideline-supported strategies for the perioperative management of insulin, including suggested indications for continuous intravenous insulin. The authors propose a strategy for determining when surgery should be delayed in patients with thyroid dysfunction and present a matrix for managing perioperative stress dose corticosteroids based on the limited evidence available.

High risk and low prevalence diseases: Thyroid storm

INTRODUCTION

Thyroid storm is a rare but serious condition that carries a high rate of morbidity and even mortality.

OBJECTIVE

This review highlights the pearls and pitfalls of thyroid storm, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence.

DISCUSSION

Thyroid storm is a challenging condition to diagnose and manage in the ED. It is characterized by exaggerated signs and symptoms of thyrotoxicosis and evidence of multiorgan decompensation, usually occurring in the presence of an inciting trigger. Clinical features of thyroid storm may include fever, tachycardia, signs of congestive heart failure, vomiting/diarrhea, hepatic dysfunction, and central nervous system disturbance. There are several mimics including sympathomimetic overdose, substance use disorders, alcohol withdrawal, acute pulmonary edema, aortic dissection, heat stroke, serotonin syndrome, and sepsis/septic shock. Ultimately, the key to diagnosis is considering the disease. While laboratory assessment can assist, there is no single laboratory value that will establish a diagnosis of thyroid storm. Clinical criteria include the Burch-Wartofsky point scale and Japan Thyroid Association diagnostic criteria. ED treatment focuses on diagnosing and managing the trigger; resuscitation; administration of steroids, thionamides, iodine, and cholestyramine; and treatment of hyperthermia and agitation. Beta blockers should be administered in the absence of severe heart failure. The emergency clinician should be prepared for rapid clinical deterioration and employ a multidisciplinary approach to treatment that involves critical care and endocrinology specialists.

CONCLUSIONS

An understanding of thyroid storm can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

Perioperative Management for Non-Thyroidal Surgery in Thyroid Dysfunction

Thyroid hormone exerts effects across all organ systems. Hence, patients with thyroid dysfunction are at a risk of numerous complications. The stresses encountered during the perioperative period may exacerbate underlying thyroid disorders, potentially precipitating decompensation, and even death. Thus, it is of the utmost importance for the clinician to comprehend the mechanisms by which thyroid disease may complicate surgery and postoperative recovery and to optimize the status of thyrotoxic and hypothyroid patients. This article describes the adverse effects of thyroid dysfunction in patients undergoing nonthyroid surgery and recommends treatment approaches aimed at appropriate build-up to decrease perioperative risk.

Thyroid emergencies

Myxedema coma and thyroid storm are among the most common endocrine emergencies presenting to general hospitals. Myxedema coma represents the most extreme, life threatening expression of severe hypothyroidism with subjects presenting with deteriorating mental status, hypothermia, and multiple organ system abnormalities. It typically appears in patients with pre-existing hypothyroidism via a common pathway of respiratory decompensation with CO₂ narcosis leading to coma. Without early and appropriate therapy, there is often a fatal outcome. It is a clinical diagnosis based on history and physical findings at presentation and not on any objective thyroid laboratory tests. Clinically based scoring systems have been proposed to aid in the diagnosis. While a relatively rare syndrome, the typical patient is an elderly woman (thyroid hypofunction being much more common in women) who may or may not have a history of previously diagnosed or treated thyroid dysfunction. Thyrotoxic storm or thyroid crisis also is a rare condition and it too reflects a clinical diagnosis. Diagnosis is based upon the appearance of severe hyperthyroidism accompanied by elements of systemic decompensation. Based upon the prospect of high mortality without aggressive treatment, therapy must be initiated as early as possible in a critical care setting. There are no clues to diagnosis based upon laboratory tests alone, but several scoring systems have been developed to aid in diagnosis. The usual clinical signs and symptoms of hyperthyroidism will be present along with more exaggerated clinical manifestations affecting the cardiovascular, gastrointestinal, and central nervous systems. A multi-pronged treatment approach has been recommended and has been associated with improved outcomes.

Evaluation of the Macy Catheter®: a rectal catheter for rapid medication and fluid administration

INTRODUCTION

Health care providers are increasingly challenged to balance cost considerations for devices, drugs, and staffing all while continuing to provide excellent care. Patients in both the post-acute and acute care settings often require fluid and/or medication when their oral route is compromised and vascular access may not be warranted or immediately accessible. The rectum is an underutilized administration point that can be accessed with speed and relative ease. Areas Covered: Literature reviews of pharmaceutical, medical, and nursing references reveal current and historical science that validates the rectal route as a means of alternative administration for fluids and medications. Expert Commentary: Historically the rectum has been used for medication and fluid delivery but in more recent times, use has waned due to many factors. The physiology of the rectum allows for rapid and reliable administration of a variety of medications as well as hydration. This serves as an introduction to a novel, simple, cost effective device that allows for discreet and painless rectal administration of fluids and medications when the oral route is compromised and/or intravenous access is difficult or unnecessary. This device is used in a variety of patients in many care settings.

A Novel Approach for the Administration of Medications and Fluids in Emergency Scenarios and Settings

The available routes of administration commonly used for medications and fluids in the acute care setting are generally limited to oral, intravenous, or intraosseous routes, but in many patients, particularly in the emergency or critical care settings, these routes are often unavailable or time-consuming to access. A novel device is now available that offers an easy route for administration of medications or fluids via rectal mucosal absorption (also referred to as proctoclysis in the case of fluid administration and subsequent absorption). Although originally intended for the palliative care market, the utility of this device in the emergency setting has recently been described. Specifically, reports of patients being treated for dehydration, alcohol withdrawal, vomiting, fever, myocardial infarction, hyperthyroidism, and cardiac arrest have shown success with administration of a wide variety of medications or fluids (including water, aspirin, lorazepam, ondansetron, acetaminophen, methimazole, and buspirone). Device placement is straightforward, and based on the observation of expected effects from the medication administrations, absorption is rapid. The rapidity of absorption kinetics are further demonstrated in a recent report of the measurement of phenobarbital pharmacokinetics. We describe here the placement and use of this device, and demonstrate methods of pharmacokinetic measurements of medications administered by this method.

Thyrotoxic Storm

Thyrotoxic storm is a syndrome of exaggerated thyrotoxicosis with systemic decompensation seen in 1-2% of hospital admissions for thyrotoxicosis. The diagnosis is based on recognition of typical cardinal manifestations, but even when diagnosed and treated, mortality rates are high. Results of thyroid function tests may be no more abnormal than those seen in uncomplicated thyrotoxicosis. Often, there is a history of partially treated thyrotoxicosis, and/or decompensation related to a precipitating event such as infection, stroke, pulmonary embolism, or radioiodine therapy. Treatment must be aggressive and includes volume repletion with i.v. glucose and saline, and pressor agents may be needed. Patients belong in an intensive care unit, with a cooling blanket for hyperpyrexia. Appropriate cardiac medications are employed to control ventricular rate in those with atrial fibrillation. The thyroid is blocked by large doses of antithyroid agent. In patients unable to swallow, tablets can be crushed and given by nasogastric tube or per rectum. After antithyroid drugs are started, stable iodine as Lugol's solution is given to block further hormone release from the gland. Sodium ipodate can be used instead of iodine and has the advantage of inhibiting conversion of T4 to T3. In severe cases, thyroid hormone may be removed from the circulation by peritoneal dialysis or plasmapheresis, and cholestyramine resin may be used to bind T4 and T3 within the gastrointestinal tract. β-adrenergic antagonists such as propranolol are given, or the very short-acting β-adrenergic blocker, esmolol, has also been used with success. A Swan-Ganz catheter is used to monitor central hemodynamics, especially in patients receiving high-dose propranolol, pressors, digoxin, diuretics, and fluids. Large doses of dexamethasone have been given based on presumed increased glucocorticoid requirements in thyrotoxicosis and because adrenal reserve may be reduced. Therapy must be continued until a normal metabolic state is achieved, at which time iodine is progressively withdrawn and plans made for definitive treatment.

First Use of a New Device for Administration of Buspirone and Acetaminophen to Suppress Shivering During Therapeutic Hypothermia

Therapeutic hypothermia or targeted temperature management has been used after cardiac arrest to improve neurological outcomes and mortality. However, a side effect of temperature modulation is a centrally mediated shivering response. The Columbia Anti-Shivering Protocol sets up a systematic method of intravenous (IV) and oral medication escalation to suppress this response and preserve the benefits of this therapy. We present the case of a 59-year-old male who began shivering after therapeutic hypothermia for cardiac arrest, leading to a persistent rise in core temperature despite adequate sedation. He was also found to have gastric contents similar to coffee grounds through nasogastric tube suction. The shivering was effectively suppressed and the rising core temperature plateaued using rectal acetaminophen and buspirone administered by means of a novel device, the Macy Catheter. Also, when used in conjunction with other protocol-driven medications, the patient was able to achieve a core temperature of 33°C. The Macy Catheter appears to be a useful approach to rectally administer buspirone and acetaminophen, using an easy-to-place, nonsterile atraumatic device that requires no radiographic confirmation of placement.

An alternative for rapid administration of medication and fluids in the emergency setting using a novel device

Routes of administration for medications and fluids in the acute care setting have primarily focused on oral, intravenous, or intraosseous routes, but, in many patients, none of these routes is optimal. A novel device (Macy Catheter; Hospi Corp) that offers an easy route for administration of medications or fluids via rectal mucosal absorption (proctoclysis) has recently become available in the palliative care market; we describe here the first known uses of this device in the emergency setting. Three patients presenting to the hospital with conditions limiting more typical routes of medication or fluid administration were treated with this new device; patients were administered water for hydration, lorazepam for treatment of alcohol withdrawal, ondansetron for nausea, acetaminophen for fever, aspirin for antiplatelet effect, and methimazole for hyperthyroidism. Placement of the device was straightforward, absorption of administered medications (judged by immediacy of effects, where observable) was rapid, and use of the device was well tolerated by patients, suggesting that this device may be an appealing alternative route to medication and fluid administration for a variety of indications in acute and critical care settings.

The Brazilian consensus for the diagnosis and treatment of hyperthyroidism: recommendations by the Thyroid Department of the Brazilian Society of Endocrinology and Metabolism

INTRODUCTION

Hyperthyroidism is characterized by increased synthesis and release of thyroid hormones by the thyroid gland. Thyrotoxicosis refers to the clinical syndrome resulting from excessive circulating thyroid hormones, secondary to hyperthyroidism or due to other causes. This article describes evidence-based guidelines for the clinical management of thyrotoxicosis.

OBJECTIVE

This consensus, developed by Brazilian experts and sponsored by the Department of Thyroid Brazilian Society of Endocrinology and Metabolism, aims to address the management, diagnosis and treatment of patients with thyrotoxicosis, according to the most recent evidence from the literature and appropriate for the clinical reality of Brazil.

MATERIALS AND METHODS

After structuring clinical questions, search for evidence was made available in the literature, initially in the database MedLine, PubMed and Embase databases and subsequently in SciELO - Lilacs. The strength of evidence was evaluated by Oxford classification system was established from the study design used, considering the best available evidence for each question.

RESULTS

We have defined 13 questions about the initial clinical approach for the diagnosis and treatment that resulted in 53 recommendations, including the etiology, treatment with antithyroid drugs, radioactive iodine and surgery. We also addressed hyperthyroidism in children, teenagers or pregnant patients, and management of hyperthyroidism in patients with Graves' ophthalmopathy and various other causes of thyrotoxicosis.

CONCLUSIONS

The clinical diagnosis of hyperthyroidism usually offers no difficulty and should be made with measurements of serum TSH and thyroid hormones. The treatment can be performed with antithyroid drugs, surgery or administration of radioactive iodine according to the etiology of thyrotoxicosis, local availability of methods and preferences of the attending physician and patient.

Thyroid Storm

Thyroid storm, an endocrine emergency first described in 1926, remains a diagnostic and therapeutic challenge. No laboratory abnormalities are specific to thyroid storm, and the available scoring system is based on the clinical criteria. The exact mechanisms underlying the development of thyroid storm from uncomplicated hyperthyroidism are not well understood. A heightened response to thyroid hormone is often incriminated along with increased or abrupt availability of free hormones. Patients exhibit exaggerated signs and symptoms of hyperthyroidism and varying degrees of organ decompensation. Treatment should be initiated promptly targeting all steps of thyroid hormone formation, release, and action. Patients who fail medical therapy should be treated with therapeutic plasma exchange or thyroidectomy. The mortality of thyroid storm is currently reported at 10%. Patients who have survived thyroid storm should receive definite therapy for their underlying hyperthyroidism to avoid any recurrence of this potentially fatal condition.

Thyroid emergencies

This review presents current knowledge about the thyroid emergencies known as myxedema coma and thyrotoxic storm. Understanding the pathogenesis of these conditions, appropriate recognition of the clinical signs and symptoms, and their prompt and accurate diagnosis and treatment are crucial in optimizing survival.

Management of severe thyrotoxicosis when the gastrointestinal tract is compromised

BACKGROUND

The management of patients with severe thyrotoxicosis in the absence of a functional gastrointestinal tract represents an uncommon but significant clinical challenge associated with a high mortality rate. This article offers a literature review and discussion of the available management options in this setting.

SUMMARY

Treatment of severe thyrotoxicosis in patients unable to ingest medications by the oral route should focus on normalization of thyroid hormone levels utilizing conventional medical therapy for thyrotoxicosis, administered via non-oral routes. This includes thionamides, beta-blockers, iodine containing solutions, and glucocorticoids. When conventional medical therapy fails, plasmapheresis should be considered as a temporary therapeutic bridge until conventional therapies can be instituted effectively or emergent surgery performed.

CONCLUSION

Although a rare scenario, the management of patients with severe thyrotoxicosis in the absence of a functional gastrointestinal tract represents a challenging clinical situation. Endocrinologists and critical care physicians should be apprised of the available treatment modalities which must be instituted swiftly in order to avoid a catastrophic outcome.

Current and emerging treatment options for Graves' hyperthyroidism

Radioiodine, antithyroid drugs and surgery have been well established therapies for Graves' hyperthyroidism for several decades. However there remain large variations in practice among physicians in the preferred modality and the method of administration. Patient choice and perceptions also play a big role in the choice of treatment. Radioiodine may be given using fixed high doses or by calculated doses following uptake studies. The risks of radioiodine including eye disease and the role of prophylactic steroid therapy are discussed. The commonly used antithyroid drugs include carbimazole, methimazole and propylthiouracil; however a number of other agents have been tried in special situations or in combination with these drugs. The antithyroid drugs may be given in high (using additional levothyroxine in a block-replace regimen) or low doses (in a titration regimen). This review examines the current evidence and relative benefits for these options as well as looking at emerging therapies including immunomodulatory treatments such as rituximab which have come into early clinical trials. The use of antithyroid therapies in special situations is also discussed as well as clinical practice issues which may influence the choices.

Hyperthyroidism

Thyrotoxicosis is a condition resulting from elevated levels of thyroid hormone. In this article, the authors review the presentation, diagnosis, and management of various causes of thyrotoxicosis.

Thyrotoxicosis and thyroid storm

Thyroid storm represents the extreme manifestation of thyrotoxicosis as a true endocrine emergency. Although Grave's disease is the most common underlying disorder in thyroid storm, there is usually a precipitating event or condition that transform the patient into life-threatening thyrotoxicosis. Treatment of thyroid storm involves decreasing new hormone synthesis, inhibiting the release of thyroid hormone, and blocking the peripheral effects of thyroid hormone. This multidrug, therapeutic approach uses thionamides, iodine, beta-adrenergic receptor antagonists, corticosteroids in certain circumstances, and supportive therapy. Certain conditions may warrant the use of alternative therapy with cholestyramine, lithium carbonate, or potassium perchlorate. After the critical illness of thyroid storm subsides, definitive treatment of the underlying thyrotoxicosis can be planned.

Intravenous methimazole in the treatment of refractory hyperthyroidism

BACKGROUND

Management of a hyperthyroid patient unable to take oral or rectal medication is a difficult clinical problem. The need for an alternative parenteral route of antithyroid medication administration in thyrotoxic patients occurs in certain rare cases, such as emergent gastrointestinal surgery, bowel ileus or obstruction, or severe vomiting and diarrhea. We report a simple and successful protocol for the preparation and use of intravenous methimazole (MMI) for treatment of hyperthyroidism in patients intolerant of orally and rectally administered thionamides.

METHODS

Five hundred milligrams of methimazole USP powder was reconstituted with pH-neutral 0.9% sodium chloride solution to a final volume of 50 mL using aseptic technique, then filtered through a 0.22-microm filter. MMI injection was administered as a slow intravenous push over 2 minutes and followed by a saline flush.

CASES

A 76-year-old man, intolerant of oral and rectal medications because of an ileus and intractable diarrhea, who developed worsening thyrotoxicosis after an emergent spinal cord decompression, and a 42-year-old man with chronic liver disease and hyperthyroidism, requiring emergent exploratory laparotomy and maintenance of complete bowel rest because of persistent gastrointestinal bleeding were rendered euthyroid using intravenous MMI.

CONCLUSION

Two cases of hyperthyroidism successfully treated with a preparation of intravenous MMI are described.

Rectal Administration of Propylthiouracil in Suppository Form in Patients With Thyrotoxicosis and Critical Illness: Case Report and Review of Literature

OBJECTIVE

To report the successful management of thyrotoxicosis in a seriously ill 47-year-old man with a perforated gastric ulcer in whom oral intake was contraindicated.

METHODS

Our patient was treated with 400 mg of propylthiouracil (PTU) every 6 hours in the form of specially prepared suppositories for rectal administration, together with intravenously infused esmolol.

RESULTS

We were able to demonstrate substantial absorption of PTU administered by means of rectal suppositories. Serum levels of PTU were maintained within the high therapeutic range for 5 days until the patient was able to tolerate orally administered therapy. The patient improved clinically during this treatment.

CONCLUSION

This case strongly supports the rectal administration of PTU in suppository form as an appropriate alternative route in any patient with thyrotoxicosis, including the critically ill patient, when oral administration is not possible.

Hyperthyroidism

The clinical spectrum of hyperthyroidism varies from asymptomatic,subclinical hyperthyroidism to the life-threatening "thyroid storm". Hyperthyroidism is a common form of thyroid disease that mimics many of the common complaints in the emergency department. The diagnosis of hyperthyroidism is often challenging due to the multitude of physical and even psychiatric complaints. Recognition and treatment by emergency physicians of severe hyperthyroidism is critical and can be life saving.

Critical issues in endocrinology

Endocrine emergencies are commonly encountered in the ICU. This article focuses on several important endocrine emergencies, including diabetic hyperglycemic states, adrenal insufficiency, myxedema coma, thyroid storm, and pituitary apoplexy. Other endocrine issues that are related to intensive care, such as intensive insulin therapy, relative adrenal insufficiency, and thyroid function test abnormalities are also covered in detail.

Perioperative management of the thyrotoxic patient

Preoperative thyrotoxicosis is a potentially life-threatening condition that requires medical intervention before surgery. Most patients are undergoing thyroidectomy for persistent thyrotoxicosis, usually Graves' disease, either having contraindications to or failing medical therapy. Fewer patients are undergoing nonthyroidal surgery that is likely urgent or emergent. The choice of treatment depends on the time available for preoperative preparation, the severity of the thyrotoxicosis, and the impact of any current or previous therapies. Generally treatment is directed at a combination of targets in the thyroid hormone synthetic, secretory, and peripheral pathway with concurrent treatment to correct any decompensation of normal homeostatic mechanisms. Thionamides are the preferred initial treatment unless contraindicated, but do require several weeks to render a patient euthyroid. beta-Blockers should always be used unless absolutely contraindicated because they improve thyrotoxic symptoms especially of the cardiovascular system. Other agents including iodine and steroids can be used if rapid preparation is required or more severe thyrotoxicosis is present. The goal of therapy is to render the patient as close as possible to clinical and biochemical euthyroidism before surgery. Overall, the morbidity and mortality of adequately prepared patients is low.

Perioperative evaluation and management of the patient with endocrine dysfunction

Whenever possible, endocrine disorders should be identified and evaluated prior to surgery. A plan for perioperative management of diabetes should be based on the type of diabetes, what diabetes medications are taken, the status of diabetes control, and what type of surgery is planned. Perioperative management of diabetes must include bedside glucose monitoring. Patients with mild hypothyroidism can safely proceed with elective surgery. Elective surgery should be postponed for patients with moderate or severe hypothyroidism. Patients who have mild hyperthyroidism can undergo elective surgery with preoperative beta blockade. Elective surgery should not be done on patients with moderate or severe hyperthyroidism until they are euthyroid. Patients with pheochromocytoma need to be identified and properly treated before surgery to prevent perioperative cardiovascular complications. Patients who take endogenous steroids should have the status of their HPA axis determined prior to surgery. If the patient is undergoing moderate or major surgical stress and has documented or presumed HPA suppression, then stress doses of steroids should be give perioperatively.

Rectal administration of propylthiouracil in hyperthyroid patients: comparison of suspension enema and suppository form

Previous studies have described the therapeutic effects of propylthiouracil (PTU) and methimazole in normal subjects after rectal suppositories. The goal of our study was to compare the pharmacokinetic and pharmacologic effects of a suppository and suspension form of PTU given per rectum. Fifteen newly diagnosed hyperthyroid patients of both genders (ages 21 to 55 years) were randomly given the drug as follows: group 1 (n = 7), a single enema (400 mg of PTU in 90 mL of sterile water) and group 2 (n = 8), two suppositories of polyethylene glycol base (200 mg of PTU in each). The pharmacokinetic study revealed earlier time to peak levels (T(max)) and significantly greater maximal peak levels (C(max)) in group 1 than in group 2, (85.71 +/- 12.12 minutes vs. 172.5 +/- 26.24 minutes for T(max) and 3.89 +/- 0.34 vs. 2.01 +/- 0.38 microg/mL, p < 0.05 for C(max), respectively). However, the area under the curve (635.16 +/- 105.71 vs. 377.87 +/- 68.09 microg x min/mL) was not statistically different between both groups. Both forms induced a significant decrease in serum free triiodothyronine (FT(3)) levels and an increase in serum rT(3) levels shortly after administration. Four subjects reported a bitter taste 5-10 minutes after receiving the drug. PTU can be effectively absorbed via the rectal route. The enema form appeared to provide better bioavailability than the suppository form. However, both preparations exhibited comparable therapeutic effect.

Endocrine problems in the chronically critically ill patient

The endocrine adaptations to critical illness are varied. In the diabetic patient, counterregulatory hormones predispose to insulin resistance and hyperglycemia, a derangement accentuated by the use of glucocorticoids and enteral or parenteral nutrition. Thyroid abnormalities include the euthyroid sick syndrome, which may manifest as a low T3, low T4, low TSH, or all three. Illness in patients with pre-existing hypothyroidism or hyperthyroidism may precipitate myxedema coma or thyroid storm, respectively. The most important issue related to calcium is that of acute hypercalcemia, which, in the intensive care unit, usually is caused by malignancy and dehydration. Hyponatremia, a frequently encountered electrolyte disturbance, is evaluated best and treated according to volume status.

Antithyroid drugs for the treatment of hyperthyroidism caused by Graves' disease

Therapy for Graves' disease is not straightforward and often involves complex decision making. Long-term antithyroid drug therapy is appealing because it is nonablative, but it is not for everyone. The physician must weigh the advantages and disadvantages of antithyroid drug treatment and help the patient arrive at an individualized therapeutic strategy that is appropriate and cost-effective.

Rectal administration of iodide and propylthiouracil in the treatment of thyroid storm

We administered potassium iodide and propylthiouracil per rectum, in conjunction with intravenous dexamethasone and propranolol, for emergent treatment of a patient in thyroid storm with small bowel obstruction. Shortly after initiation of this treatment, the patient successfully underwent two emergent surgical procedures for resection of an intestinal volvulus with advanced peritonitis. Serum levels of iodide and propylthiouracil showed substantial absorption of these drugs via the rectal route. Measurement of 24-h urinary-free iodide indicated that the bioavailability of potassium iodide delivered by retention enema was at least 40%. Parenteral iodide preparations have been unavailable in the past, and continue to be difficult to obtain emergently. Rectal administration of inorganic iodide is an effective, readily available and less expensive alternative to parenteral sodium iodide for patients in thyroid storm with upper gastrointestinal tract dysfunction.

Thyroid storm

Despite earlier recognition and treatment of hyperthyroidism, thyroid storm remains a life-threatening, although fortunately rare, medical emergency. Prompt recognition and aggressive treatment employing a multifaceted approach are generally effective at correcting the homeostatic decompensation that is the hallmark of thyroid storm. Research is furthering understanding of the cellular actions of thyroid hormone and may lead to additional, even more effective treatment modalities in the future.

Endocrine emergencies in pregnancy

A number of endocrine conditions and emergencies have unique characteristics when present in the pregnant woman. Often the abnormal endocrine state affects both mother and fetus and the various diagnostic and therapeutic approaches have to be altered to avoid harming the fetus. Furthermore, the pregnant state itself may alter the natural course of the underlying endocrine condition. Prolactinomas may enlarge due to the hormonal milieu of pregnancy, causing mass effects and even apoplexy. Anticipation of this possibility and prompt recognition may prevent disastrous consequences. This stimulatory state may extend to the normal pituitary, resulting in Sheehan's syndrome. An acute form of Sheehan's may go unrecognized, leading to unnecessary maternal deaths. Autoimmune endocrine disorders may sometimes be exacerbated and at other times be ameliorated during pregnancy. Witness the development of lymphocytic hypophysitis during pregnancy, a condition best left alone if it can be diagnosed without surgery. Graves's disease usually improves during pregnancy but it may occasionally flare, resulting in potentially lethal thyroid storm. The various therapeutic alternatives for hyperthyroidism are very much affected by effects on the fetus. Cushing's syndrome has very bad consequences for the fetus and must be diagnosed and treated urgently, if not emergently. Phaeochromocytomas are always endocrine emergencies requiring urgent and sometimes emergent treatment. Hyperparathyroidism is usually mild, but severe hypercalcaemia can be a true endocrine emergency. Recognition of the interactions of these endocrine conditions and their specific treatments with the complicated maternal-fetal unit makes their diagnosis and treatment simultaneously both difficult and extremely rewarding.

Pharmacokinetics of methimazole in humans

A newly developed method for extracting and measuring methimazole in biological fluids was used to study the pharmacokinetics of methimazole in two euthyroid and eight hyperthyroid subjects. The volume of distribution approximated total body water; the biological half-life was 2-3 h in euthyroid and about 6 h in hyperthyroid patients. Total clearance was lower in hyperthyroid patients than in euthyroid subjects, and it did not increase after thyroid function was normalized. Bioavailability in euthyroid subjects was greater than 1 but only 0.5 in hyperthyroid subjects. The reasons for these observed differences are not known.

Clinical management of patients with hyperthyroidism

The clinical management of the hyperthyroid patient is controversial, because there is no perfect treatment. Factors that influence the choice of therapy include the patient's age, sex, and type of hyperthyroidism, as well as patient and physician preference.

Antithyroid drugs

Over the past four decades, a great deal has been learned about the pharmacology and mechanisms of action of antithyroid drugs. Their ability to inhibit hormone biosynthesis involves complex interactions with thyroid peroxidase and thyroglobulin, many of which are still poorly understood. Their spectrum of activity is much wider than previously thought, and a number of clinically important extrathyroidal actions have been identified. Despite a greater appreciation for the intricacies of antithyroid-drug pharmacology, controversies still surround the use of these agents in the treatment of thyrotoxicosis. These controversies are apt to continue until the pathophysiology of Graves' disease is fully elucidated.