Factor IV, also known as calcium ion or Ca2+, is an important substance that plays a crucial role in various biological processes. Synonyms for factor IV include calcium, calcium cation, calcium ionized, and ionized calcium. These terms are often used interchangeably in scientific literature and medical reports. Calcium is necessary for muscle contraction, blood clotting, and nerve function. High levels of ionized calcium can cause hypercalcemia, a condition that can lead to fatigue, nausea, and confusion. Low levels of ionized calcium can cause hypocalcemia, which can result in muscle weakness, seizures, and even cardiac arrest. Understanding the various synonyms for factor IV is essential for accurate communication in scientific and medical fields.