Calcium homeostasis in the body is a complex interplay between several different hormones or hormone-like substances, such as parathyroid hormone (PTH), Vitamin D, and calcitonin. Disorders of calcium metabolism are encountered pretty frequently in routine clinical practice. Hypocalcemia is not as frequently encountered as hypercalcemia, but it can be potentially life-threatening if not appropriately recognized and treated promptly. Hypocalcemia is said to be present when the total serum calcium concentration is less than 8.8 mg/dl. The disorder may be acquired or inherited but its presentation can vary- from asymptomatic to life-threatening. Hypocalcemia is commonly seen in hospitalized patients and for the most part, is mild in nature and only requires supportive treatment.
The causes of hypocalcemia can be divided into three broad categories:
PTH DEFICIENCY (low or low normal serum PTH)
There is no literature on the quantification of hypocalcemia in general. However, the reported prevalence of transient hypocalcemia after thyroidectomy varies between 6.9 to 49% and between 0.4 to 33% for permanent hypocalcemia. In general, renal failure by far remains the most common cause of hypocalcemia followed by vitamin D deficiency, magnesium deficiency, acute pancreatitis, etc.
Calcium is vital for many body functions like cell function, nerve transmission, bone structure, intracellular signaling and blood coagulation. The amount of calcium absorbed from the GI tract is usually matched by renal excretion. The levels of calcium are rigidly controlled by vitamin D, parathyroid hormone and calcitonin. Parathyroid hormone enhances osteoclastic bone resorption and distal tubular reabsorption of calcium. In addition, it mediates absorption of calcium from the intestine. Vitamin D is known to regulate PTH release, intestinal absorption of calcium and also medicares PTH stimulated bone reabsorption. Calcitonin on the other hand lowers levels of calcium. Hypocalcemia is a common cause of tetany and neuromuscular irritability. An alkaline environment lowers calcium levels and induces tetany, whereas an acidic envirionment is protective.
The history and physical exam of patients with suspected hypocalcemia should be conducted with two underlying principles in mind. First, to uncover the potential manifestations of hypocalcemia like:
The second part of history and physical should focus on determining the cause of hypocalcemia such as recent head and neck surgery, family history of similar problems, history of kidney disease, alcohol abuse (hypomagnesemia), psychiatric history, etc.
Work up of hypocalcemia can be thought of in the following parts:
Management of hypocalcemia can be divided into two broad categories:
Check a magnesium level when faced with hypocalcemia since its an important and easily correctable cause of hypocalcemia.
Because there are many causes, the diagnosis and management of hypocalcemia is best done with an interprofessional team. Consultations from many specialists are required because of the diverse causes and effects. In each case, one needs to treat hypocalcemia and the primary disorder responsible for it. An endocrinologist and an internist should always be involved. While the condition can be managed in an outpatient setting, close follow up is required. The pharmacist has to make sure that the patient is not on any medications that are aggravating the electrolyte disorder. A dietary consult should be ordered for patients with renal failure and hypocalcemia in order to prevent the symptoms. Patients need to be educated about the symptoms of hypocalcemia like muscle weakness and paresthesias so that they can seek treatment. Open communication between the team members is vital to prevent the morbidity of hypocalcemia.
|||Postsurgical Hypoparathyroidism: A Systematic Review., Kakava K,Tournis S,Papadakis G,Karelas I,Stampouloglou P,Kassi E,Triantafillopoulos I,Villiotou V,Karatzas T,, In vivo (Athens, Greece), 2016 May-Jun [PubMed PMID: 27107072]|
|||Systematic review and meta-analysis of predictors of post-thyroidectomy hypocalcaemia., Edafe O,Antakia R,Laskar N,Uttley L,Balasubramanian SP,, The British journal of surgery, 2014 Mar [PubMed PMID: 24402815]|
|||Accuracy of methods to estimate ionized and "corrected" serum calcium concentrations in critically ill multiple trauma patients receiving specialized nutrition support., Dickerson RN,Alexander KH,Minard G,Croce MA,Brown RO,, JPEN. Journal of parenteral and enteral nutrition, 2004 May-Jun [PubMed PMID: 15141404]|
|||Diagnosis and management of hypocalcaemia., Cooper MS,Gittoes NJ,, BMJ (Clinical research ed.), 2008 Jun 7 [PubMed PMID: 18535072]|