[1] Other causes of hypercalcemia include sarcoidosis, tuberculosis, Paget disease, multiple endocrine neoplasia (MEN), vitamin D toxicity, familial hypocalciuric hypercalcaemia and certain medications such as lithium and hydrochlorothiazide.

[1] The neuromuscular symptoms of hypercalcaemia are caused by a negative bathmotropic effect due to the increased interaction of calcium with sodium channels.

[6] Other symptoms include cardiac arrhythmias (especially in those taking digoxin), fatigue, nausea, vomiting (emesis), loss of appetite, abdominal pain, & paralytic ileus.

[10] In extreme cases of primary hyperparathyroidism, removal of the parathyroid gland after surgical neck exploration is the only way to avoid death.

Humoral hypercalcemia of malignancy involves the tumor releasing a hormone which increases calcium mobilization (most commonly parathyroid hormone-related protein (PTHrP)) into the circulation.

[22] The combination of PTHrP driven osteoclast activation and calcium reabsorption by the kidneys causes hypercalcemia associated with malignancy (humoral type).

[22] Tumor bone metastasis releases local cytokines including IL-6, IL-8, IL-11, interleukin-1 beta, TNF alpha and macrophage inflammatory protein.

Chronic elevation of calcium with absent or mild symptoms often points to primary hyperparathyroidism or Familial hypocalciuric hypercalcemia.

For those who has underlying malignancy, the cancers may be sufficiently severe to show up in history and examination to point towards the diagnosis with little laboratory investigations.

Intact PTH (iPTH, biologically active parathyroid hormone molecules) is measured with immunoradiometric or immunochemoluminescent assay.

Elevated (or high-normal) iPTH with high urine calcium/creatinine ratio (more than 0.03) is suggestive of primary hyperparathyroidism, usually accompanied by low serum phosphate.

Normal PTHrP is suggestive of multiple myeloma, vitamin A excess, milk-alkali syndrome, thyrotoxicosis, and immobilisation.

[25] Abnormal heart rhythms can also result, and ECG findings of a short QT interval[26] suggest hypercalcaemia.

[31] Calcium ion levels can remain high for weeks if untreated and lead to an array of medical issues.

[31] There are also cases of hypercalcemia reported due to dogs ingesting rodenticides containing a chemical similar to calcipotriene found in psoriasis cream.

Plants such as Cestrum diurnum, and Solanum malacoxylon contain ergocalciferol or cholecalciferol which cause the onset of hypercalcemia.

[29] In certain outdoor environments, animals such as horses, pigs, cattle, and sheep experience hypercalcemia commonly.

[30] Hypercalcemia is most common in grazing lands at altitudes above 1500 meters where growth of plants like Trisetum flavescens is favorable.

[30] Even if small amounts are ingested over long periods of time, the prolonged high levels of calcium ions have large negative effects on the animals.

[30] The issues these animals experience are muscle weakness, and calcification of blood vessels, heart valves, liver, kidneys, and other soft tissues, which eventually can lead to death.