Tenofovir Disoproxil Fumarate (TDF) in HIV PEP Can Cause These Electrolyte Abnormalities; Liraglutide Does Not
Tenofovir disoproxil fumarate (TDF), a component of HIV post-exposure prophylaxis regimens, can cause hypokalemia (low potassium), hyperchloremia (high chloride), and low bicarbonate through proximal renal tubular dysfunction and distal renal tubular acidosis. Liraglutide does not cause these electrolyte disturbances.
HIV PEP Medications and Renal Tubular Effects
The preferred HIV PEP regimens include either bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) or dolutegravir plus tenofovir (either TAF or TDF formulation) plus emtricitabine or lamivudine 1. When TDF is used, it carries specific renal risks.
Mechanism of TDF-Induced Electrolyte Abnormalities
TDF causes renal toxicity through two distinct mechanisms:
- Proximal renal tubular dysfunction (Fanconi syndrome): Results in phosphate, glucose, and amino acid wasting, plus impaired bicarbonate reabsorption leading to normal anion gap metabolic acidosis 2, 3
- Distal renal tubular acidosis: Causes inability to acidify urine (pH >5.5), leading to metabolic acidosis with hypokalemia and hyperchloremia 4
The classic triad you're asking about—low potassium, high chloride, and low bicarbonate—represents a hyperchloremic normal anion gap metabolic acidosis, which is the hallmark of TDF-induced renal tubular dysfunction 4, 3.
Clinical Severity and Monitoring
The FDA label explicitly warns about Fanconi syndrome with "severe hypophosphatemia" and renal tubular injury 2. Case reports document:
- Severe hypokalemia requiring hospitalization, including one cardiac arrest 5
- Recurrent hypokalaemic paralysis from distal RTA 4
- Life-threatening complications when potassium drops severely 5
However, a manufacturer safety review found that among 32 cases of grade 3/4 hypokalemia, only 4 had medically significant conditions, all of which improved with management 6.
Key Monitoring Requirements for TDF-Based PEP
The FDA mandates assessment of:
- Serum creatinine and estimated creatinine clearance
- Urine glucose and urine protein
- Serum phosphorus (in patients with chronic kidney disease)
These should be checked prior to initiation and during use on a clinically appropriate schedule 2. The CDC guidelines note that routine follow-up of serum creatinine is not necessary unless baseline tests are abnormal or specific clinical indications are present 1.
Important Clinical Pitfall
Persistent or worsening bone pain, extremity pain, fractures, or muscular pain/weakness may indicate proximal renal tubulopathy and should prompt immediate renal function evaluation 2. These symptoms can precede obvious laboratory abnormalities.
Reversibility
The renal tubular dysfunction is typically reversible upon discontinuation of TDF 4. One case report showed dramatic improvement within 24 hours of potassium correction after stopping tenofovir 4.
Liraglutide and Electrolyte Effects
Liraglutide, a GLP-1 receptor agonist used for diabetes and weight management, does not cause hypokalemia, hyperchloremia, or low bicarbonate. The recent cardiovascular outcomes study comparing liraglutide and dulaglutide across different CKD stages made no mention of these electrolyte disturbances 7. These are not recognized adverse effects of GLP-1 receptor agonists.
Clinical Bottom Line
If a patient on HIV PEP develops low potassium, high chloride, and low bicarbonate:
- Suspect TDF-induced renal tubular dysfunction (either proximal or distal RTA)
- Check urine pH (>5.5 suggests distal RTA), urine glucose, urine protein, and serum phosphorus
- Assess for symptoms of proximal tubulopathy (bone/muscle pain, weakness)
- Consider switching from TDF to TAF formulation, as TAF has lower renal toxicity risk 1
- Correct electrolytes and monitor closely
- The condition should improve after stopping TDF
Do not attribute these electrolyte abnormalities to liraglutide if the patient is taking both medications—the culprit is the TDF component of HIV PEP.