Dynamic assessment of parathyroid function in acute malaria

Area of Science:

• Endocrinology
• Infectious Diseases
• Mineral Metabolism

Background:

• Acute malaria is associated with altered mineral metabolism.
• The parathyroid hormone (PTH) system's response to hypocalcaemia in malaria is not well understood.
• Hypocalcaemia can be induced by citrate, commonly used in blood transfusions.

Purpose of the Study:

• To investigate the dynamic parathyroid response to induced hypocalcaemia in patients with acute malaria.
• To compare the PTH response in malaria patients versus healthy volunteers.
• To assess the potential resistance to calcium-chelating effects in malaria.

Main Methods:

• Serum intact parathormone (PTH) and whole-blood ionised calcium were measured.
• A variable-rate tri-sodium citrate infusion was used to induce sustained hypocalcaemia (0.20 mmol L-1 below baseline for 120 min).
• The study included six Malaysian patients with acute malaria and 12 healthy controls.

Main Results:

• Malaria patients had lower baseline ionised calcium but similar baseline PTH levels compared to controls.
• Achieving target hypocalcaemia was slower in malaria patients, requiring more citrate.
• The PTH response (delta PTH/delta Ca2+) and steady-state PTH levels during hypocalcaemia were similar in both groups.

Conclusions:

• Malaria patients have a decreased ionised calcium 'set point' for basal PTH secretion.
• The PTH response to acute hypocalcaemia is normal in malaria.
• Malaria patients appear relatively resistant to the calcium-chelating effects of citrated blood products, possibly due to skeletal resistance.