A Construction Worker's Sudden Paralysis: Understanding Thyroid-Related Muscle Weakness

Table of Contents

• Case Presentation: The 27-Year-Old Man
• Initial Examination Findings
• Laboratory Test Results
• Understanding the Differential Diagnosis
• How Your Body Manages Potassium
• Reaching the Correct Diagnosis
• Clinical Implications for Patients
• Study Limitations
• Patient Recommendations
• Source Information

Case Presentation: The 27-Year-Old Man

A 27-year-old construction worker arrived at the emergency department because he couldn't move his legs. His symptoms began three days earlier with muscle aches in his upper legs, which he initially attributed to his physically demanding job.

On the morning of his hospital visit, he woke up completely unable to lift his legs to get out of bed or stand. He also noticed weakness in his arms, though it was less severe than in his legs. The patient had no history of trauma, back pain, or changes in sensation.

He had moved from El Salvador to Boston five months earlier and reported several concerning symptoms since his relocation:

• Increasing difficulty falling and staying asleep
• Loose stools without abdominal pain, nausea, or vomiting
• Approximately 11 pounds (5 kg) of unintentional weight loss
• Trembling in his hands for several months

Four days before presentation, he began taking an herbal supplement called Nervitran to manage stress. He had no significant medical history, took no prescription medications, and had no family history of similar episodes beyond a maternal aunt who had experienced unspecified weakness.

Initial Examination Findings

On examination, doctors found:

• Blood pressure: 144/79 mm Hg (mildly elevated)
• Heart rate: 96 beats per minute (slightly fast)
• Temperature normal at 36.2°C (97.2°F)
• Oxygen saturation: 99% on room air
• Conjunctival injection (redness in both eyes)
• Muscle weakness graded on a medical scale:
  • Arm strength: 4/5 (mild weakness)
  • Leg strength: 3-5/5 (moderate to severe weakness)
• Increased patellar reflexes (3+)
• Fine tremor in both hands, more prominent on the left side

Laboratory Test Results

The patient's blood tests revealed several abnormalities:

• Severely low potassium: 1.8 mmol/L (normal range: 3.4-5.0 mmol/L)
• Elevated liver enzymes:
  • Alanine aminotransferase: 67 U/L (normal: 7-33)
  • Aspartate aminotransferase: 54 U/L (normal: 9-32)
  • Alkaline phosphatase: 156 U/L (normal: 30-100)
• Mildly elevated creatine kinase: 382 U/L (normal: 60-400), suggesting some muscle damage
• Elevated aldolase: 9.9 U/L (normal: <7.7), another marker of muscle involvement
• Slightly elevated blood sugar: 141 mg/dL (normal: 70-110)

His electrocardiogram showed sinus tachycardia (fast heart rate), incomplete right bundle-branch block, and nonspecific ST-segment and T-wave abnormalities.

After receiving 60 milliequivalents of potassium chloride orally, his potassium level normalized to 4.2 mmol/L within three hours, and his muscle weakness completely resolved.

Understanding the Differential Diagnosis

The medical team considered multiple possible causes for the patient's severe hypokalemia (low potassium levels) and muscle weakness. The differential diagnosis included:

• Renal potassium loss: Conditions where the kidneys waste too much potassium
  • Diuretic use (though patient denied taking any)
  • Vomiting or gastrointestinal losses
  • Genetic conditions like Gitelman's or Bartter's syndrome
  • Magnesium deficiency
  • Renal tubular acidosis
• Nonrenal potassium loss: Potassium leaving through other routes
  • Diarrhea (which the patient reported)
  • Excessive sweating
• Intracellular shift: Potassium moving from blood into cells
  • Medication effects
  • Thyrotoxic periodic paralysis (TPP)
  • Familial hypokalemic periodic paralysis

The rapid response to a relatively small dose of potassium suggested an intracellular shift rather than total body potassium deficiency.

How Your Body Manages Potassium

Potassium is essential for proper nerve and muscle function. Your body contains approximately 3,500 millimoles of potassium, with 98% located inside cells and only 2% in the bloodstream.

The sodium-potassium pump (Na+/K+-ATPase) actively maintains this distribution. A typical Western diet provides about 100 mmol of potassium daily, which your body must handle efficiently to prevent dangerous spikes in blood potassium levels.

Your kidneys excrete approximately 90% of excess potassium, with the remaining 10% eliminated through stool and sweat. This complex system can be disrupted by various medical conditions, medications, and genetic factors.

Reaching the Correct Diagnosis

The medical team determined that thyrotoxic periodic paralysis (TPP) was the most likely diagnosis based on several key factors:

• Demographics: The patient was a 27-year-old male of Latin American descent, which matches the typical profile for TPP
• Symptoms: His weight loss, tremor, insomnia, and diarrhea suggested hyperthyroidism (overactive thyroid)
• Rapid response: His quick recovery after potassium administration characteristic of intracellular shift disorders
• Exclusion of alternatives: No family history of periodic paralysis, no medication use that would explain symptoms

TPP is an acquired condition most common in Asian and Latin American men aged 20-50. It involves increased sensitivity of the sodium-potassium pump, driving potassium into cells and causing profound weakness.

Research involving over 2,000 Chinese patients with Graves' disease (537 with TPP) has identified genetic variants that increase susceptibility to this condition. The patient's electrocardiogram abnormalities were also more consistent with TPP than genetic forms of periodic paralysis.

Clinical Implications for Patients

This case illustrates several important points for patients:

• Sudden muscle weakness requires immediate medical attention
• Potassium imbalances can cause serious neurological symptoms
• Thyroid disorders can present with diverse symptoms including:
  • Muscle weakness
  • Weight loss despite normal appetite
  • Tremors
  • Sleep disturbances
  • Gastrointestinal issues
• Cultural factors matter - TPP disproportionately affects certain ethnic groups
• Herbal supplements should be used cautiously as they may interact with underlying conditions

The good news is that TPP can be effectively treated by addressing the underlying thyroid condition, unlike genetic forms of periodic paralysis which often lead to progressive weakness.

Study Limitations

This case report has several limitations that patients should understand:

• It describes a single patient's experience, which may not apply to everyone
• No 24-hour urine collection was performed to precisely measure potassium excretion
• The patient's thyroid function tests weren't provided in the case details
• Long-term follow-up information wasn't included
• The herbal supplement Nervitran wasn't analyzed for potential contaminants

Case reports are valuable for educating physicians about unusual presentations but don't provide the same evidence level as large controlled studies.

Patient Recommendations

Based on this case, patients should:

1. Seek immediate care for sudden muscle weakness or paralysis
2. Share complete medical history including:
   • All symptoms, even seemingly unrelated ones
   • Dietary changes and weight fluctuations
   • All medications and supplements, including herbal products
   • Family medical history
   • Recent travel or relocation
3. Follow up appropriately after initial treatment - potassium levels may need monitoring
4. Request thyroid testing if experiencing multiple symptoms including:
   • Unexplained weight loss
   • Rapid heartbeat
   • Tremors
   • Anxiety or sleep disturbances
   • Muscle weakness
5. Be cautious with supplements - discuss with your doctor before starting any new product

Source Information

Original Article Title: Case 13-2024: A 27-Year-Old Man with Leg Weakness

Authors: Andrew S. Allegretti, M.D., Cynthia L. Czawlytko, M.D., Nikolaos Stathatos, M.D., and Peter M. Sadow, M.D., Ph.D.

Publication: The New England Journal of Medicine, April 25, 2024

DOI: 10.1056/NEJMcpc2312728

This patient-friendly article is based on peer-reviewed research from Massachusetts General Hospital case records. The original article appeared in the New England Journal of Medicine, a highly respected medical publication.