Hypokalemic periodic paralysis (HPP) is a neuromuscular disorder characterized by periodic skeletal muscle weakness that can cause respiratory muscle failure and even death. The prevalence of HPP is 1 in 100,000 cases. Muscle weakness depends on changes in serum potassium level (<3.5 mmol/dL) which can be due to primary or secondary causes. Primary causes are generally autosomal dominant, while secondary causes include diuretic use, loss from the gastrointestinal tract, renal tubular acidosis (RTA), primary hyperaldosteronism, Barter’s syndrome, hyperthyroidism, and hypothyroidism.
Renal tubular acidosis refers to a transport defect characterized by the kidney’s inability to excrete acid (H+) and reabsorb bicarbonate (HCO3-) with the clinical syndrome of metabolic acidosis with a normal anion gap, hyperchloremia, and impaired urine acidification. Renal tubular acidosis can be caused by primary causes due to genetic mutations or secondary causes. Renal tubular acidosis can occur associated with various systemic disorders such as Sjogren’s syndrome, Systemic Lupus Erythematosus (SLE), and thyroid disorders.
A 58-year-old woman was referred from Soewandi Hospital with hypokalemia and hypothyroidism. She had a complaint of weakness in all four limbs for the last day. The patient has had a history of hypothyroidism since three years ago and is still on treatment. For the last three years, she has been hospitalized seven times because of repeated hypokalemia. The patient previously had no complaints of vomiting or diarrhea. The examination showed blood pressure of 110/70 mmHg, pulse rate of 98 ×/m, a temperature of 36.8 °C, and respiratory rate of 20 ×/m”motor strength 2 in all four extremities. The ECG examination showed 1st degree AV block. Laboratory examination found hypokalemia and metabolic acidosis with a normal anion gap of 13.8 meq/L, urine pH 8.0, urine anion gap 41 mmol/h. FT4 1.89 ng/dL, TSH 1.21 IU/mL. Anti TPO 20.6 IU/mL, ANA profile: strong positive SS-A (Ro), Ro-52, SS-B (La) which indicates Sjogren’s syndrome.
Based on the diagnostic criteria of the American European Consensus Group Criteria of Sjogren’s syndrome, this patient only had ocular symptoms (dry eyes), oral symptoms (dry mouth), and positive Anti-SSA (Ro) and Anti-SSB (La) autoantibodies. In this patient, several examinations to exclude the possibility of SLE, rheumatoid arthritis, and tests that support the diagnosis of Sjogren’s syndrome could not be performed, including ANA test, rheumatoid factor, Schirmer test, salivary gland biopsy.
Quadriparesis is a neurological condition characterized by weakness in all four limbs. Management of quadriparesis in HPP Administration of potassium chloride 0.5“1.0 mEq/kg which can increase motor strength in all four extremities. The return of potassium concentration to normal levels maintains the balance of cation and anion ion channel gates in the process of excitation and inhibition of muscle cells.
Based on the symptoms of hypokalemia, weakness in all four extremities, metabolic acidosis with a normal anion gap, positive urine anion gap, and alkaline urine pH, the patient is diagnosed with periodic hypokalemia and renal tubular acidosis. In the presence of objective complaints of dry eyes and dry mouth for more than three months, positive anti-SSA (Ro) anti-SSB (La) autoantibodies can be suspected to lead to a Sjogren’s syndrome. This patient needs further examination to rule out the diagnosis of SLE, rheumatoid arthritis, and additional examinations that support the diagnosis of Sjogren’s syndrome, including salivary gland biopsy, and Schirmer test.
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aStudy Program of Clinical Pathology, Faculty of Medicine, 51¶¯Âþ, Surabaya, Indonesia
bDepartment of Clinical Pathology, Faculty of Medicine, 51¶¯Âþ “ Dr. Soetomo General Academic Hospital, Surabaya, Indonesia
