What causes a salty taste in the mouth?

Salty Taste in the Mouth: Causes and Evaluation

A salty taste in the mouth most commonly results from altered salivary composition due to chronic kidney disease, dehydration, xerostomia (dry mouth), or medications, and requires evaluation of renal function, hydration status, and oral health to identify the underlying cause.

Primary Causes

Chronic Kidney Disease and Renal Dysfunction

• CKD patients have significantly elevated concentrations of sodium, potassium, chloride, phosphorus, urea, and creatinine in their saliva compared to healthy individuals, which directly causes a salty or altered taste sensation 1.
• The increased blood urea nitrogen (BUN) levels in renal failure lead to higher salivary pH and altered buffering capacity, contributing to taste disturbances 1.
• Approximately one-third of hemodialysis patients experience bad breath and altered taste due to urea in saliva being converted to ammonia 1.
• Patients with CKD should undergo evaluation of serum electrolytes, BUN, and creatinine levels to assess the degree of renal impairment 1.

Xerostomia and Salivary Disorders

• Dry mouth (xerostomia) is a frequent cause of taste alterations, including salty taste, particularly in hemodialysis patients, older adults, and those on multiple medications 1.
• Xerostomia results from reduced salivary flow, minor salivary gland fibrosis and atrophy, fluid intake restriction, mouth breathing, and xerostomizing drugs 1.
• Xerostomia significantly increases the likelihood of salt taste disability (OR 2.42; 95% CI 1.44-4.07), with even greater risk in adults over 60 years (OR 3.63; 95% CI 1.72-7.63) 2.
• The interaction between xerostomia and edentulism (complete tooth loss) further increases the chance of salt taste disability 2.

Dehydration and Electrolyte Imbalances

• Dehydration concentrates electrolytes in saliva, leading to a salty taste perception 1.
• Patients should be assessed for fluid status, particularly those with restricted fluid intake, oliguria, or high stomal/stool losses 1.
• Sodium depletion or excess can both contribute to taste alterations through changes in salivary composition 1.

Medications

• Drugs are common offenders in taste dysfunction, including medications that cause xerostomia or alter salivary composition 3.
• Anticholinergic medications directly impair salivary function and can contribute to taste alterations 4.
• Acetylcholinesterase inhibitors used in Alzheimer's disease can cause altered salivary production 5.
• Certain medications contribute to electrolyte imbalances that affect taste perception 3.

Secondary and Contributing Factors

Oral Health Conditions

• Periodontal disease, dental caries, missing teeth, and edentulism are associated with salt taste disability 2.
• Poor oral hygiene and dental calculus formation (common in CKD patients due to elevated salivary calcium, phosphorus, and magnesium) can contribute to taste alterations 1.
• Oral and gum diseases can affect taste perception through local inflammatory changes 5.

Age-Related Changes

• Normal aging leads to alterations in gustatory sensation and decreased salivary flow rates, contributing to taste disturbances including salty taste 1, 4.
• Older adults have diminished sense of taste for various reasons including physiological changes, disease, and medication use 1.
• This can paradoxically lead to increased use of salt at the table to enhance food palatability, creating a cycle of altered taste perception 1.

Metabolic and Systemic Conditions

• Diabetes and hyperglycemic crises can cause electrolyte disturbances affecting taste 1.
• Metabolic disturbances can alter the cycle of regeneration of chemoreceptors 3.
• Viral infections, head injuries, and radiation can damage taste receptors 3.

Clinical Evaluation Algorithm

Initial Assessment

1. Obtain detailed medication history to identify xerostomizing drugs, anticholinergics, or medications causing electrolyte imbalances 3.
2. Assess hydration status and fluid intake patterns, particularly in patients with restricted fluid intake or high losses 1.
3. Evaluate for symptoms of renal dysfunction: fatigue, nausea, changes in urination, edema 1.
4. Perform oral examination looking for signs of xerostomia, periodontal disease, dental caries, and missing teeth 2.

Laboratory Evaluation

• Order comprehensive metabolic panel including sodium, potassium, chloride, calcium, magnesium, BUN, and creatinine to assess renal function and electrolyte status 1.
• Consider 24-hour urine collection for electrolyte losses if indicated 1.
• Evaluate for diabetes with glucose and HbA1c if not previously diagnosed 1.

Specialized Testing

• Salivary flow rate assessment if xerostomia is suspected 1.
• Objective taste testing may be warranted in persistent cases 2.
• Referral to nephrology if renal impairment is identified 1.

Management Approach

Treating Underlying Causes

• Address renal dysfunction through appropriate nephrology referral and management 1.
• Optimize hydration status with appropriate fluid replacement, using glucose-saline solutions (sodium concentration ≥90 mmol/L) in patients with high GI losses 1.
• Review and modify medications that contribute to xerostomia or electrolyte imbalances when possible 3.

Symptomatic Relief

• Sodium bicarbonate mouth rinses can improve taste symptoms in CKD patients (66% found beneficial with 40% preference over other solutions; P=0.005 for symptom improvement) 6.
• Ensure adequate hydration and salivary flow through frequent sips of appropriate fluids 1.
• Dental hygiene optimization and treatment of periodontal disease 2.
• Use of saliva substitutes or stimulants for xerostomia 1.

Dietary Modifications

• Limit dietary sodium intake to <2,000 mg (87 mmol) per day, or 1,500 mg (65 mmol) per day in patients with hypertension or CKD 1.
• Avoid processed and canned foods high in sodium 1.
• Use herbs and spices instead of salt for flavoring 1.
• Caution against salt substitutes containing potassium chloride in patients with hyperkalemia 1.

Important Caveats

• Taste alterations may persist for several months even after treating the underlying condition, as chemoreceptor regeneration takes time 3.
• Abrupt and strict sodium restriction in patients accustomed to high-sodium intake can lead to anorexia and malnutrition; introduce restrictions gradually 1.
• Silent or subclinical renal impairment may be present without obvious symptoms, making laboratory evaluation essential 1.
• The interaction of multiple factors (age, medications, oral health, systemic disease) often contributes to taste alterations, requiring comprehensive evaluation 2.
• Dental professionals should be involved in identifying patients with taste alterations, as this may indicate increased risk of systemic diseases requiring salt reduction 2.