Is Polyuria Common in Primary Hyperparathyroidism (PHPT)?
Polyuria is not a commonly reported symptom in modern presentations of PHPT, particularly in older adults, as the disease now predominantly presents asymptomatically in countries with routine biochemical screening. 1
Clinical Presentation in Contemporary PHPT
The clinical landscape of PHPT has shifted dramatically:
In developed countries with routine screening (United States, Canada, Europe), PHPT predominantly presents as an asymptomatic disorder without classic symptoms like polyuria. 1
The symptomatic presentation with polyuria, polydipsia, and other target organ manifestations is now primarily seen in countries without routine biochemical screening (China, India). 1
When polyuria does occur in PHPT, it results from hypercalcemia-induced osmotic diuresis, which leads to hypovolemia, decreased glomerular filtration rate, and prerenal azotemia—similar to the mechanism seen in hyperglycemia. 1
Age-Related Considerations
Older adults with PHPT are even less likely to experience polyuria as a presenting symptom for several important reasons:
The renal threshold for calcium excretion increases with age, making osmotic diuresis less likely to occur at the same calcium levels that would trigger symptoms in younger patients. 1
Elderly patients often present with non-specific symptoms like weight loss and fatigue rather than classic polyuria/polydipsia. 1
Thirst mechanisms are more likely to be impaired in older adults, further reducing the likelihood of recognizing or reporting polyuria. 1
Renal Manifestations That Are Common
While polyuria itself is uncommon, renal involvement in PHPT manifests differently:
Asymptomatic kidney stones occur in approximately 7% of asymptomatic PHPT patients, significantly higher than the 1.6% prevalence in the general population. 2
Hypercalciuria is present in most PHPT patients (>250-300 mg/day), representing increased filtered calcium load rather than symptomatic polyuria. 2, 3
Reduced renal function (eGFR <60 mL/min/1.73 m²) is a recognized complication and serves as a surgical indication for parathyroidectomy. 4, 5, 6
Clinical Pitfalls to Avoid
Do not confuse hypercalciuria with symptomatic polyuria—these are distinct entities. Hypercalciuria in PHPT reflects increased calcium filtration and is typically asymptomatic, detected only through 24-hour urine collection. 2, 3
In older adults presenting with urinary symptoms, consider urinary incontinence rather than polyuria as the more likely manifestation, particularly in women with diabetes or other comorbidities. 1
If an older patient with known PHPT develops polyuria, evaluate for moderate-to-severe hypercalcemia (>12 mg/dL), which presents with polyuria, polydipsia, nausea, vomiting, and confusion—this represents a more severe disease state requiring urgent management. 7