Renal Manifestations of Primary Hyperparathyroidism (PHPT)

• Patients with PHPT have some degree of renal dysfunction or symptoms:
  • In approximately 80% of the cases of PHPT
• The renal manifestations implicated with PHPT are:
  • Decreased glomerular filtration rate
  • Hypercalciuria
  • Nephrolithiasis
  • Nephrocalcinosis
  • Impaired urinary concentrating ability:
    • Sometimes leading to:
      • Polyuria
      • Polydipsia
      • Nocturia
  • Reduced fractional phosphate reabsorption:
    • Leading to hypophosphatemia
  • Increased urinary exertion of magnesium
• Nephrolithiasis:
  • Was previously reported in approximately 40% to 80% of patients:
    • But now occur only in about 20% to 25% of the cases
  • The pathophysiology is thought to be related to:
    • The filtered load of calcium in the glomerulus:
      • That increases proportionately with the degree of hypercalcemia
  • Most renal stones in patients with PHPT:
    • Are composed of calcium oxalate:
      • Although slightly alkaline urine:
        • May favor the precipitation of calcium phosphate stones
  • Stone formers are more likely to be hypercalciuric:
    • But less than one-third of the hypercalciuric patients with PHPT:
      • Actually develop renal stones
  • Hypercalciuria:
    • Is not a predictor of nephrolithiasis in patients with PHPT:
      • Is no longer considered as an indication for surgery
• Nephrocalcinosis:
  • Which refers to renal parenchymal calcification:
    • Is found in less than five percent of patients:
      • Is more likely to lead to renal dysfunction
• The incidence of hypertension is variable;
  • Anywhere between 30% to 50% of patients with PHPT
• Hypertension:
  • Appears to be more common in older patients
  • Correlates with the magnitude of renal dysfunction
  • In contrast to other symptoms:
    • Is least likely to improve after parathyroidectomy
• Another plausible explanation of the origin of hypertension in patients with PHPT:
  • Is the synthesis of parathyroid hypertensive factor:
    • That triggers an increase in blood pressure
• The elevated levels of PTH is also linked with the disruption in the:
  • Renin-angiotensin- aldosterone system 

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