Thyrotoxic periodic paralysis in pregnancy with impaired glucose tolerance: a case report and discussion of management issues

Diagnosis, management and outcomes of primary hypokalemic periodic paralysis during pregnancy

Primary hypokalaemic periodic paralysis during pregnancy has been rarely reported. Four pregnant women with the acute onset of flaccid paralysis presented between January 2018 and December 2021. Focussed history and physical examination helped an appropriate radiological and laboratory investigation plan to be made. All women recovered within 4-7 days of potassium supplementation. Supplemental potassium continued until delivery. A pain management plan with continuous epidural infusion helped in avoiding stress-induced hypokalaemia. None of the women developed an episode of muscle weakness during the intervening period. In conclusion, a focussed history and targeted laboratory investigation are needed to diagnose primary hypokalaemic periodic paralysis. Early administration of oral or intravenous potassium is crucial in improving fetomaternal outcomes.

Neuromuscular disorders in pregnancy

Many neuromuscular disorders preexist or occur during pregnancy. In some cases, pregnancy unmasks a latent hereditary disorder. Most available information is based on case reports or series or retrospective clinical experience or patient surveys. Of special interest are pregnancy-induced changes in disease course or severity and likelihood for baseline recovery of function postpartum. Labor and delivery present special challenges in many conditions that affect skeletal but not smooth (uterine) muscle; so labor complications must be anticipated. Anesthesia for cesarean section surgery requires special precautions in many disorders. The types of conditions reviewed are broad and include examples of autoimmune, hereditary, and compressive/mechanical processes. Disorders include carpal tunnel syndrome and other focal neuropathies, Bell palsy, myasthenia gravis, and other neuromuscular junction disorders, acute and chronic inflammatory neuropathy, hereditary and acquired muscle diseases, spinal muscular atrophy, amyotrophic lateral sclerosis, channelopathies, autonomic neuropathy, and dysautonomia. Many commonly used therapies have fetal animal but no proven human toxicity concerns, complicating treatment and risk decisions. Weaning off effective therapeutic agents or preemptive aggressive treatment or surgery prior to planned pregnancy is an option in some conditions.

Fatality after cardiac arrest in thyrotoxic periodic paralysis due to profound hypokalemia resulting from intravenous glucose administration and inadequate potassium replacement

BACKGROUND

Thyrotoxic periodic paralysis (TPP) is a variant of periodic paralysis (PP) that occurs in patients with underlying mutations in genes for cation channels, if they develop thyrotoxicosis. It is disabling, and fatalities sometimes occur. Here, we present a patient with TPP who developed hypokalemic paralysis that was probably aggravated by the administration of a carbohydrate, probably contributing to, if not causing, a fatal outcome.

SUMMARY

A 30-year-old Chinese patient received (131)I treatment for Graves' disease (GD) in our hospital. Three days later in the middle of the night, he developed aggravating paralytic symptoms after a heavy evening meal. The next morning, he was seen in a small clinic and was treated with 1250 mL 5% glucose containing 25 mL 10% potassium chloride (KCl). By early afternoon, he had not improved and was transferred to a city hospital, arriving with grade I muscle strength and severed facial and bulbar paralysis that was shortly followed by cardiac arrest with failure of resuscitation. Shortly before he died, his serum K(+) was 1.15 mEq/L (normal=3.5-5).

CONCLUSIONS

We postulate that severe hypokalemia developed in our patient in part in response to the high intravenous glucose load that he received. We advocate caution against using intravenous glucose solutions for potassium administration in patients with TPP and recommend a review of guidelines suggesting this form of treatment. In rural settings with limited resources, we favor oral potassium, not to exceed 100 mEq per day, and transfer to a modern medical facility in settings where muscle weakness is developing in patients with TPP.

Thyroid disorders in pregnancy

Maternal hypothyroidism, thyroid antibody positivity, and hyperthyroidism may pose significant risks in terms of pregnancy complications and fetal adverse effects. Treatment of hyperthyroidism with thionamides remains the standard of care during pregnancy. Radioiodine use is contraindicated in pregnancy, including in the treatment of thyroid carcinoma, because of the risk of fetal hypothyroidism, subsequent cognitive impairment, and even fetal death. Normal thyroid function during pregnancy is essential to ensure delivery, to the best extent possible, of a healthy baby, which may be achieved with frequent monitoring of thyroid function during gestation and cautious adjustment of medications during treatment.

Novel etiopathophysiological aspects of thyrotoxic periodic paralysis

Thyrotoxicosis can lead to thyrotoxic periodic paralysis (TPP), an endocrine channelopathy, and is the most common cause of acquired periodic paralysis. Typically, paralytic attacks cease when hyperthyroidism is abolished, and recur if hyperthyroidism returns. TPP is often underdiagnosed, as it has diverse periodicity, duration and intensity. The age at which patients develop TPP closely follows the age at which thyrotoxicosis occurs. All ethnicities can be affected, but TPP is most prevalent in people of Asian and, secondly, Latin American descent. TPP is characterized by hypokalemia, suppressed TSH levels and increased levels of thyroid hormones. Nonselective β adrenergic blockers, such as propranolol, are an efficient adjuvant to antithyroid drugs to prevent paralysis; however, an early and definitive treatment should always be pursued. Evidence indicates that TPP results from the combination of genetic susceptibility, thyrotoxicosis and environmental factors (such as a high-carbohydrate diet). We believe that excess T(3) modifies the insulin sensitivity of skeletal muscle and pancreatic β cells and thus alters potassium homeostasis, but only leads to a depolarization-induced acute loss of muscle excitability in patients with inherited ion channel mutations. An integrated etiopathophysiological model is proposed based on molecular findings and knowledge gained from long-term follow-up of patients with TPP.

Analytic review: thyrotoxic periodic paralysis: a review

Thyrotoxic periodic paralysis (TPP) is an unusual complication of hyperthyroidism that frequently presents in a dramatic fashion, necessitating treatment in an emergency department or admission to an intensive care unit. Thyrotoxic periodic paralysis is characterized by transient, recurrent episodes of flaccid muscle paralysis affecting proximal more severely than distal muscles. Thyrotoxic periodic paralysis is most commonly a complication of Graves' disease in Asian males, although in recent decades, an increasing number of patients from all racial and ethnic backgrounds have been reported. Thyrotoxic periodic paralysis has a higher predilection for men than women despite the fact that thyroid disease is more frequently diagnosed in women. The presence of both hypokalemia and elevated levels of triiodothyronine (T3) and thyroxine (T4) are important diagnostic features during the acute episode. Treatment of TPP involves 2 steps, immediate action to reverse the paralysis followed by measures to prevent future attacks by restoration of a euthyroid state. Although the mainstay of treating an acute attack of TPP is correction of hypokalemia to avoid fatal cardiac arrhythmias and reverse muscle weakness, it must be appreciated by treating physicians that patients with TPP do not have a total body deficiency of potassium. Close attention must be given to potassium replacement as overly aggressive treatment can result in hyperkalemia. Correction of hypokalemia and the underlying thyrotoxic state usually results in amelioration of the acute attack. This review summarizes the epidemiology, clinical manifestations, pathogenesis, diagnosis, and treatment of TPP.

Insulin resistance in subjects with a history of thyrotoxic periodic paralysis (TPP)

BACKGROUND

Hyperinsulinaemia has been suggested as an important factor for developing hypokalaemic paralysis in patients with thyrotoxic periodic paralysis (TPP). Since hyperinsulinaemia is a common feature of insulin resistance, there may be a causal relationship between insulin resistance and TPP.

OBJECTIVE

To compare insulin sensitivity between subjects with a history of TPP and others with a history of thyrotoxicosis without periodic paralysis.

METHODS

Insulin sensitivity measured by euglycaemic hyperinsulinaemic clamp and 75-g oral glucose tolerance test (OGTT) were performed nonselectively in 10 subjects with a history of TPP (TPP group) and 10 age- and sex-matched subjects with a history of simple thyrotoxicosis (control group). All participants had euthyroidism and fasting plasma glucose of < 5.55 mmol/l at the time of the study.

RESULTS

Body mass index and waist circumference of the TPP group were higher than that of the control group. One of 10 (10%) subjects in the TPP group and 6 of 10 (60%) in the control group had BMI of < 23 kg/m2. Areas under the curve (AUC) of plasma glucose after OGTT were comparable, while the AUC of serum insulin of the TPP group was higher than in the control group. The TPP group had lower insulin sensitivity than the control group.

CONCLUSION

The subjects with a history of TPP were more obese and had lower insulin sensitivity than those with a history of simple thyrotoxicosis. Insulin resistance with compensatory hyperinsulinaemia may be a key feature of the pathogenesis of TPP.