Abstract
Introduction
Due to a COVID-related job loss resulting in financial and food insecurity, a 28-year-old woman initiated a diet consisting solely of one cup of ramen noodles daily for twenty-two months, leading to 27 kg of weight loss. Ramen noodles are low in calories and lack key nutrients, including potassium, chloride, and vitamin B12.
Case description
The patient presented to the emergency department with acute, worsening weakness and paresthesias in her left wrist and hand. Exam revealed no other abnormalities aside from a cachectic appearance. Labs revealed marked hypokalemia, hypochloremia, lactic acidosis, a mixed metabolic alkalosis with respiratory acidosis, and low levels of zinc and copper. An EKG revealed a prolonged QT interval. After a neurology and psychiatry consult, the patient was admitted for failure to thrive with malnutrition, peripheral neuropathy, hypokalemia, and an acid-base disorder. An MRI of the brain was unremarkable. Studies of other nutritional deficiencies, autoimmune conditions, and sexually transmitted infections were unremarkable. The patient received food and vitamin supplementation, was monitored for re-feeding syndrome, and had a significant recovery.
Discussion
After stroke, spinal injury, multiple sclerosis, and the most common focal mononeuropathies were ruled out, the clinical focus turned to nutritional deficiencies, the most significant of which was hypokalemia. Prior research has shown that severe hypokalemia can lead to weakness. It has also shown that chronically insufficient dietary intake is a common cause of hypokalemia. This case, with its partial paralysis of a unilateral upper extremity, may add to the known clinical manifestations of hypokalemia. We review the role of hypokalemia and hypochloremia in acid-base dynamics. Etiologies and clinical manifestations of cobalamin, thiamine, pyridoxine, and copper deficiencies, along with lead toxicity, are also discussed. Diagnostic clarity of mononeuropathies in the context of malnutrition and hypokalemia can be aided by urine potassium levels prior to repletion, neuroimaging that includes the cervical spine, and follow-up electromyography.
1
Introduction
A 28-year-old woman presented to our emergency department (ED) with acute, painless left wrist and hand weakness and numbness after twenty-two months of a diet consisting solely of one cup of ramen noodles per day. Initial laboratory results revealed potassium 2.2 mmol/L, lactic acid 5.0 mmol/L, PCO2 66.8 mmHg and bicarbonate 40 mmol/L. She was admitted to our inpatient service for further imaging, blood testing, electrolyte repletion, vitamin supplementation, and cardiac monitoring. She was subsequently discharged with symptomatic improvement. We review various etiologies of myeloneuropathy related to poor nutritional intake, including the effects of hypokalemia from a potassium-poor diet.
2
Case presentation
A right-handed 28-year-old Chinese-American woman with no significant medical history presented to the ED with five hours of worsening, sudden-onset weakness in her left wrist and hand. She reported increasing difficulty with wrist flexion, wrist extension, grasp strength, finger abduction, and flexion/extension in each finger of her left hand. The weakness was associated with mild paresthesia, though she sensed pain, temperature, and pressure. Her symptoms started on the day of presentation and progressed rapidly over thirty minutes. She denied recent trauma, fevers, headaches, aphasia, slurred speech, ataxia, confusion, facial droop, seizures, visual disturbances, or vomiting. She also denied personal or family history of similar prior episodes.
Review of systems revealed weight loss of 27 kg over the preceding twenty-two months. She stated that due to financial constraints from a COVID-related job loss, she had been consuming a low-calorie diet consisting of one cup of instant ramen noodles each day. She did not take any medications.
ED vital signs included a temperature of 97.4 F, blood pressure 109/71 mmHg, heart rate 79 beats per minute (BPM), respiratory rate 18 breaths per minute, and oxygen saturation 100% on room air. With a weight of 30.4 kg and height of 154.9 cm, her body mass index was 12.7. Physical exam revealed a well-appearing but cachectic young woman fully alert and oriented with no signs of trauma. Neurological findings included significant motor deficits concerning for an isolated wrist drop ( Table 1 ). The remainder of her neurological, dermatological, musculoskeletal, cardiovascular, pulmonary, and abdominal exams were unremarkable.
| Dimension | Initial Exam | Post-Treatment Exam |
|---|---|---|
| Left | ||
| Fingers Strength |
|
|
| Thumb Strength |
|
|
| Wrist Strength |
|
|
| Brachioradialis Strength |
|
|
| Elbow Strength |
|
|
| Forearm Strength |
|
|
| Shoulder Strength |
|
|
| Sensation | Pain, temperature, and light touch intact throughout | Pain, temperature, and light touch intact throughout |
Initial laboratory results ( Table 2 ) revealed moderate-severe hypokalemia, lactic acidosis, and a normal pH with an acid-base analysis significant for mixed metabolic alkalosis and respiratory acidosis in excess of what might be expected to compensate for metabolic alkalosis. Thyroid studies were within normal ranges. COVID-19 antigen and PCR tests were negative.
| Laboratory Test | Value [with normal ranges] |
|---|---|
| VBG pH | 7.42 |
| VBG PCO2 | 66.8 [38–50 mmHg] |
| VBG PO2 | 31.2 [29–35 mmHg] |
| VBG HCO3 | 38.3 [23–30 MMOL/L] |
| VBG Lactic acid | 5.0 [0.5–1.6 MMOL/L] |
| VBG Base Excess | 15.4 [0–2 MMOL/L] |
| VBG Na | 139 [135–149 MMOL/L] |
| VBG K | 2.2 [3.4–4.8 MMOL/L] |
| VBG Chloride | 80 [93–105 MMOL/L] |
| Chem Na | 136 [135–149 MMOL/L] |
| Chem K | 2.6 [3.6–5.1 MMOL/L] |
| Chem Chloride | 81 [93–105 MMOL/L] |
| Chem HCO3 | 40 [22–32 MMOL/L] |
| Chem BUN | 29.92 [7–21 mg/dL] |
| Chem Creatinine | 1.0 [0.3–1.1 mg/dL] |
| Chem Glucose | 75 [59–140 mg/dL] |
| Calcium, Serum | 10.2 [8.2–10.1 mg/dL] |
| Magnesium, Serum | 2.4 [1.6–2.2 mg/dL] |
| Phosphorus, Serum | 3.6 [2.2–5.5 mg/dL] |
| WBC | 5.6 [4.8–10.8 k/UL] |
| RBC | 3.68 [4.20–5.40 M/UL] |
| HGB | 12.6 [12.0–16.0 g/dL] |
| HCT | 35.7 [37.0–47.0%] |
| MCV | 97.0 [81.0–99.0 FL] |
| MCH | 34.2 [27.0–31.0 PG] |
| MCHC | 35.3 [33.0–37.0%] |
| RDW | 11.8 [11.4–16.4%] |
| Platelet Count | 295 [150–450 k/UL] |
| Neutrophil Count | 48.8 [37.9–70.5%] |
| Lymphocyte Count | 45.8 [19.8–47.7%] |
| Monocyte Count | 4.3 [2.7–11.7%] |
| Eosinophil Count | 0.2 [0.3–5.9%] |
| Basophil Count | 0.7 [0.1–2.4%] |
| Imm Granulocyte % | 0.2 [%] |
| Albumin, Serum | 4.8 [3.5–5.2 g/gL] |
| Bilirubin, Total | 0.8 [0.2–1.4 mg/dL] |
| Bilirubin, Direct | 0.1 [0.0–0.2 mg/dL] |
| AST, Serum | 58 [10–33 IU/L] |
| Alkaline Phosphatase, Serum | 45 [36–112 IU/L] |
| ALT, Serum | 55 [6–47 IU/L] |
| Total Protein, Serum | 7.7 [5.6–7.6 g/DL] |
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