Sample stability and heparin interference in ionized calcium and ionized magnesium measurements in horses using the Stat Profile Prime Plus co-oximetry electrolyte analyzer

Serum Ionised Calcium and Ionised Magnesium in Dairy Cows and Their Associations With the Incidence and Severity of Postpartum Metritis

Peripartum is a critical period for dairy cows during which they may undergo postpartum diseases such as hypocalcaemia and metritis. Determination of serum total calcium (tCa) is widely used to monitor imbalances in this period, but determination of total magnesium (tMg) and ionised forms of both cations (iCa and iMg) has been less studied. In the present work, 42 healthy cows and 53 cows diagnosed with mild or moderate metritis were included. Serum samples were collected 10 days prepartum and 1, 3 and 10 days postpartum to determine tCa, iCa, tMg and iMg concentrations, as well as their corresponding ratios. Our results show that hypocalcaemia and hypermagnesaemia occur on Day 1 postpartum in cows that stayed healthy and cows undergoing metritis. Cows with moderate metritis showed lower serum concentrations of iCa and iMg throughout the period. Low values of prepartum iCa and iMg at 10 days before calving were associated with later development of metritis and therefore could represent potential prognostic indicators. In conclusion, the determination of iCa, tMg and iMg in serum, in addition to tCa, could offer a more comprehensive view of the ionic status of the periparturient dairy cow and may provide information about the risk of suffering uterine diseases.

The Laboratory and Clinical Perspectives of Magnesium Imbalance

Magnesium (Mg2+) is a predominantly intracellular cation that plays significant roles in various enzymatic, membrane, and structural body functions. As a calcium (Ca2+) antagonist, it is imperative for numerous neuromuscular activities. The imbalance of body Mg2+  concentration leads to clinical manifestations ranging from asymptomatic to severe life-threatening complications. Therefore, the contribution of Mg2+ measurement regarding various laboratory and clinical aspects cannot be ignored. Mg2+ is often described as the forgotten analyte. However, its close relationship with body potassium (K+), Ca2+, and phosphate homeostasis proves that Mg2+ imbalance could co-exist as the root cause or the consequence of other electrolyte disorders. Meanwhile, several preanalytical, analytical, and postanalytical aspects could influence Mg2+ measurement. This review highlights Mg2+ measurement's laboratory and clinical issues and some analyte disturbances associated with its imbalance. Understanding this basis could aid clinicians and laboratory professionals in Mg2+ result interpretation and patient management.