An unusual case of recurrent hypokalemic paralysis in an adolescent: Answers

A 15-year-old Caucasian girl presented to the emergency department with a 2-day history of generalized body weakness, abdominal pain, and an inability tomove her extremities. She reported poor appetite, fatigue, dizziness, generalized joint pains, back pain, nausea, and two episodes of vomiting. She denied having a history of diarrhea, dysuria, blood in the urine, changes in urine output, and frequent or urgent urination. She also denied having a history of recent upper respiratory symptoms, headaches, chest pain, difficulty breathing, leg or joint swelling. There was no history of seizures, rash, syncope, speech difficulty, lightheadedness or numbness. She denied recent intense exercise, starvation, high-carbohydrate and/or low-potassium diet, and ingestion of an illicit drug or alcohol. Her past medical history was significant for a history of medullary sponge kidneys (MSK) and renal tubular acidosis (RTA) diagnosed 2 years ago in her home town when being worked up for generalized muscle weakness. She reported having had three previous episodes of similar presentations over the past 2 years and was told that she had low serum potassium levels. All three episodes necessitated a hospital admission lasting for about a day and the episode resolved with intravenous potassium supplements and hydration. The patient’s mother was unsure of what the serum potassium levels had been between those episodes. She had been placed on daily potassium and bicarbonate supplements for the past 1 year, but had not been taking it for the past 2 months. She was born at full term with a birth weight of 7 lbs 6 oz (3.35 kg). Her growth and development was appropriate with no history of failure to thrive or repeated hospitalizations for dehydration episodes. There was no history of deafness, polyuria or bone loss. There was no history suggestive of autoimmune disorders. She was sexually active with one male partner and had no history of sexually transmitted disease. Her family history was insignificant for consanguinity, similar problems, low serum potassium or any other renal diseases. On physical examination, her vitals were as follows: blood pressure (BP) 114/56 mmHg manually in the right upper extremity with an adequate sized cuff (95th percentile BP: 126/82 mmHg), pulse 100/min, respiratory rate 16/min, temperature 36.6° Celsius, weight 58.9 kg (70th centile), height 157 cm (20th centile), body mass index 24 kg/m (82nd centile), and SPO2 99 % on room air. She was alert and oriented. She was otherwise well-developed and wellnourished. Extraocular movements were normal. There was no periorbital edema. There was no moon facies. There was no cervical adenopathy. She did have mild neck tenderness with restricted neck movements. Speech was not slurred. Heart soundswere normal with regular rhythm andwith nomurmurs. Lungs were clear to auscultation with symmetric chest expansion and no use of accessory muscles. Abdomen examination showed mild generalized tenderness. Bowel sounds were normal. There was marked tenderness in both lower extremities. Deep tendon reflexes were present but diminished and the muscle strength was 2 in all 4 extremities. Tone was diminished in all four extremities, more so in the lower extremities. Pain sensation was intact. There were no cranial nerve deficits. Laboratory investigations showed normal complete blood count and liver function test. Initial arterial blood gas showed pH 7.18, pCO2 28 mmHg, PO2 129 mmHg, HCO3 10 mmol/ The answers to these questions can be found at http://dx.doi.org/10.1007/ s00467-014-2929-x.