Calcium is tightly regulated by the parathyroid hormone (PTH). In response to low calcium levels, PTH levels rise, and conversely if there are high calcium levels then PTH secretion declines. However, in the setting of absent, decreased, or ineffective PTH hormone, the body loses this regulatory function, and hypocalcemia ensues. Hypoparathyroidism is commonly due to surgical destruction of the parathyroid glands. Hypoparathyroidism may also be due to autoimmune problem. Some causes of hypocalcaemia are as follows:

Mechanism
Physiologically, blood calcium is tightly regulated within a narrow range for proper cellular processes. Calcium in the blood exists in three primary states: bound to proteins (mainly albumin), bound to anions such as phosphate and citrate, and as free (unbound) ionized calcium; all of these forms are ionised. Only the unbound calcium is physiologically active. Normal blood calcium level is between 8.5 and 10.5 mg/dL (2.12 to 2.62 mmol/L) and that of unbound calcium is 4.65 to 5.25 mg/dL (1.16 to 1.31 mmol/L). Diagnosis
Because a significant portion of calcium is bound to albumin, any alteration in the level of albumin will affect the measured level of calcium. A corrected calcium level based on the albumin level is: Corrected calcium (mg/dL) = measured total Ca (mg/dL) + 0.8 * (4.0 - serum albumin [g/dL]). Since calcium is also bound to small anions, it may be more useful to correct total calcium for both albumin and the anion gap. Management
Management of this condition includes:
Intravenous calcium gluconate 10% can be administered, or if the hypocalcaemia is severe, calcium chloride is given instead.
A nasal septum perforation is a medical condition in which the nasal septum, the bony/cartilaginous wall dividing the nasal cavities, develops a hole or fissure. This may be brought on directly, as in the case of nasal piercings, or indirectly, as by long-term topical drug application, including intranasal ethylphenidate, methamphetamine, cocaine, crushed prescription pills, or decongestant nasal sprays, chronic epistaxis, excessive nose picking and as a complication of nasal surgery like septoplasty or rhinoplasty. Much less common causes for perforated nasal septums include rare granulomatous inflammatory conditions like granulomatosis with polyangiitis. It has been reported as a side effect of anti-angiogenesis drugs like bevacizumab. Signs and symptoms
A perforated septum can vary in size and location, and is usually found deep inside the nose. It may be asymptomatic, or cause a variety of signs and symptoms. Small perforations can cause a whistling noise when breathing. Larger perforations usually have more severe symptoms. These can be a combination of crusting, blood discharge, difficulty breathing, nasal pressure and discomfort. The closer the perforation is to the nostrils, the more likely it is to cause symptoms. Cause
Infective causes include syphilis, leprosy, and rhinoscleroma. Non-infective causes include cocaine abuse, an in situ foreign body, chronic use of topical nasal decongestants, methamphetamine, facial trauma, or may develop as a consequence of nasal surgery. Treatment
Septal perforations are managed with a multitude of options. The treatment often depends on the severity of symptoms and the size of the perforations. Generally speaking anterior septal perforations are more bothersome and symptomatic.