From the Guidelines
Low PTH levels should be managed by adjusting dialysate calcium concentration to stimulate PTH production and prevent adynamic bone disease, with a target intact PTH level of at least 100 pg/mL (11.0 pmol/L) 1. When managing low PTH levels, it is essential to consider the underlying cause and the patient's overall clinical context. In patients with chronic kidney disease, low PTH levels can be associated with adynamic bone disease, which can be stimulated by reducing the dialysate calcium concentration to 1.5 to 2.0 mEq/L 1. This approach can help increase bone turnover and prevent low-turnover bone disease. However, it is crucial to monitor PTH levels closely to avoid overstimulation and the development of high-turnover bone disease.
Key considerations in managing low PTH levels include:
- Adjusting dialysate calcium concentration to stimulate PTH production 1
- Monitoring intact PTH levels to avoid overstimulation and high-turnover bone disease 1
- Maintaining a target intact PTH level of at least 100 pg/mL (11.0 pmol/L) 1
- Being aware of the potential risks and benefits of different dialysate calcium concentrations, including the risk of cardiac arrhythmias with lower calcium dialysates 1
By taking a thoughtful and individualized approach to managing low PTH levels, clinicians can help prevent complications and improve patient outcomes. Regular monitoring of serum calcium, phosphorus, and magnesium levels is also essential to ensure that the patient's mineral metabolism is well-controlled 1.
From the Research
Definition and Characteristics of Low PTH
- Low PTH, also known as hypoparathyroidism, is characterized by hypocalcemia, hyperphosphatemia, and low or inappropriately normal levels of parathyroid hormone (PTH) 2.
- PTH is a key calcium regulating hormone essential for calcium homeostasis, vitamin D-dependant calcium absorption, renal calcium reabsorption, and renal phosphate clearance 2.
Causes of Low PTH
- The most common cause of hypoparathyroidism is iatrogenic in the setting of anterior neck surgery 2, 3.
- Other causes include autoimmune diseases, genetic abnormalities, destruction or infiltrative disorders of the parathyroids, hypomagnesemia, and hypermagnesemia 2.
Symptoms and Diagnosis of Low PTH
- Symptoms of hypocalcemia include neuromuscular irritability, perioral numbness, paresthesias, tingling, seizures, and bronchospasm 2, 3.
- Diagnosis is made through a comprehensive history, physical examination, and relevant biochemical investigation 2.
Treatment of Low PTH
- Treatment of symptomatic or profound asymptomatic hypocalcemia involves rapid intravenous administration of calcium and oral supplementation of vitamin D metabolites 2.
- Oral calcium and vitamin D analogs are critical in the treatment of hypocalcemia, and thiazide diuretics can enhance renal calcium reabsorption and increase serum calcium 2.
- PTH replacement therapy has emerged as a new treatment option, which can improve serum calcium and lower serum phosphate levels, as well as reduce the doses of calcium and calcitriol supplementation required 3, 4, 5.
- Recombinant human PTH(1-84) has been approved in the United States and Europe for the management of hypoparathyroidism, but its effect on long-term complications is still being evaluated 3, 5.