Please register or login to view the chart

Hypocalcemia-Low calcium

Commonest cause of hypocalcaemia is HYPOPARATHYROIDISM -Common 
↓ calcium , ↑ phosphate and ↓ or inappropriately N levels of PTH.Surgical Idiopathic Neonatal Familial Autoimmune. Metal deposition ( Iron , copper , aluminium ) Post radiation Infiltrative Functional ( in low magnesium ) Congenital

Vitamin D related –↓ ed absorption ( dietary , malabsorption ) ↓ed synthesis ( lack of sun , liver failure , renal failure , 1 alpha hydroxylase deficiency ) Impaired Vit D metabolism ( usually drug related ) Genetic syndromes.Vid D deficiency should be considered in a patient with cl features of rickets , osteomalacia , hypophosphataemia , ↑ AlkPo4 or ↑ PTH levels

In relation to phosphate –Hypomagnesemia Acute pancreatitis Any critical illness as burns or sepsis Osteomalacia Overhydration.CKD (common cause of low Ca ) Phosphate therapy hypoparathyroidism rhabdomyolyis

In relation to magnesium –Inhibits PTH secretion and also resistance to PTH action ↓ Magnesium can be due to GI loss Renal cause Medications related (Diuretics , Alcohol) Cisplastin (chemotherapy). Inhibitors of bone resorption (calcitonin and Bisphosphonates ) Loop diuretics Glucocorticoids Interference with Vit-D metabolism 
( anti-convulsants ) PPIs- can lead to low magnesium leading to hypocalcaemia

Resistance to para thyroid action –Mutations in PTH signalling pathway- PTH resistance Pseudohypoparathyroidism Low calcium and phosphate patient are short with round face
and short 4th metacarpal Renal insufficiency Medications ( block osteoclastic bone resorption) include Bisphosphonates

Extravascular calciun deposition –Hungry bone syndrome Pancreatitis Rhabdomyolysis Tumour lysis syndrome Widespread osteoblastic metastasis

Neuromuscular excitability –Tingling (fingers , toes , tips) Numbness Cramps Spasms (carpopedal ) layngopspam-stridor Tetany (repetitive discharge of peripheral nerve after a single stimulus) Seizure threshold reduced

Clinical signs –Chvostek’s sign-twitching and/ or contracture of the facial muscles – tapping on the facial N at a specific point on face
 Trousseaus signs- carpopedal spasm occurring after a few minutes of inflation of a sphygnomanometer cuff above systolic blood pressure
 ( both specific and sensitive for hypocalcaemic tetany )

Symptoms – Vit d related Bone pain Fracture Proximal myopathy

Hypoparathyroidism related –Mental retardation Personality disturbance Extrapyramidal signs Cataracts Papilloedema.

Other manifestations –ECG Delayed repolarisation- prolonged QT int Refractory CCF ( if underlying cardiac dis ) Subcapsular cataract Dry flaky skin Brittle dystrophic nails Alopecia Movement disorder ( basal ganglia calcification ) rickets in children (low Ca + low phosphate as in Vit D deficiency )

Investigations –Vit D level Parathyroid hormone Renal function LFTs including Amylase ECG ( prolongation of QT interval 500 ms ) Phosphate Magnesium ABG in acute presentation ( alkalosis ) Urine calcium/creatinine ratio

Secodary hyperparathyroidism –Vit D Deficiency
○ elderly
○ lack of sunlight
○ nutritional
○ malabsorption syndrome
○ liver disease or CKD Parathyroid hormone resistance
○ hypomagnesaemia
○ pseudohypoparathyroidism Drugs
○ inhibitors of bone resorption as
 bisphosphonates
 calcitonin
 denusomab
○ inhibitors of calcium and magnesium resorption as PPIs
○ altered vit D metabolism eg Phenytoin Chelation of circulating calcium 
○ acute pancreatitis
○ early rhabdomyolysis
○ massive tumour lysis
○ large blood transfusions Low ionised calcium concentrations
○ hyperventilation
○ acute severe illness

PTH-low –Reduced parathyroid function
○ hypomagnesaemia
○ drugs as cinacalcet
○ neonatal hypocalcaemia
 Parathyroid loss
○ surgery
○ autoimmune disease
○ agenesis

Parathyroid hormone ( PTH ) Stimuates osteoclasts –> bone resorption leading to ↑ Calcium and Phosphorus conc Stimulates 1 alpha hydroxylase activity in kidney –> inc in 1,23 dihydroxyvitamin D production Inhibits renal excretion of calcium Indirectly increases intestinal Ca and Ph absorption Calcium has negative feedback effect on PTH

Chronic Kidney disease ( CKD ) PTH ↑ Phosphate ↑ Magnesium normal or elevated Calcitriol ↓ 1,25 (OH)2 Vit D ↓ Creatinine ↑

Phosphate –Hypoparathyroid disorders associated with hyperphosphataemia Low serum Phosphate conc are associated with ↑↑ PTH conc as in
○ secondary hyperparathyroid states as Vit D deficiency and osteomalacia Fasting levels can be

Magnesium –Hypomagnesaemia is associated with PTH impairment Conc < 0.5 mmol/L can lead to ↓ Ca Consider in acute or chronic diarrhoea , malabsorption syndromes , alcoholism , drugs – PPI or thiazide diuretics

Ostemalacia and rickets –Normal boney matrix which is undercalcified Rickets if calcium deficiency occurs during bone growth , Osteomalacia after epiphyseal closure Bone pain , fractures and proximal myopathy Blood tests if Vit D related
○ hypocalcemia and 2ary hyperparathyroidism –> ↑ renal Ph excretion and ↓ urinary calcium –> hypophosphataemia and ↑ AlkPo4

References

  1. Hypocalcaemia Authored by Dr Colin Tidy, Reviewed by Dr Adrian Bonsall | Last edited  https://patient.info/doctor/hypocalcaemia

  2. Hypocalcemia Medscape July 2016 Manish Suneja et al
  3. Cooper, Mark S, and Neil J L Gittoes. “Diagnosis and management of hypocalcaemia.” BMJ (Clinical research ed.) vol. 336,7656 (2008): 1298-302. doi:10.1136/bmj.39582.589433.BE
  4. Fluids and electrolytes demystified Joyce Johnson et al Mc-Graw-Hill Professional
  5. Harrison’s manual of medicine Dennis L Kasper McGraw-Hill Professional
  6. Investigating hypocalcemia BMJ 2013 ; 346: f2213
  7. Hypocalcemia Henry’s Clinical Diagnosis and Management by Laboratory Methods
  8. Diagnosis and Management of hypocalcemia BMJ 2008 ;336 :1298
  9. Hypocalcemia MSD Manuals by James L.Lewis et al
  10. Secondary Hyperparathyroidism: Pathophysiology and Treatment Wissam Saliba and Boutros El-Haddad 

  11. Biochemical Investigations in Laboratory Medicine via http://www.pathology.leedsth.nhs.uk/dnn_bilm/Metabolic/Metabolicbonedisease/Osteomalacia.aspx

  12. Fong, Jeremy, and Aliya Khan. “Hypocalcemia: updates in diagnosis and management for primary care.” Canadian family physician Medecin de famille canadien vol. 58,2 (2012): 158-62. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3279267/
  13. Management of hypocalcemia ABC of Intravenous Fluids , Electrolyte Disorders and AKI Management in Adults via http://www.wasd.org.uk/wp-content/uploads/2017/03/C07-Hypocalcaemia.pdf
  14. Schafer AL, Shoback DM. Hypocalcemia: Diagnosis and Treatment. [Updated 2016 Jan 3]. In: Feingold KR, Anawalt B, Boyce A, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK279022/ ( Abstract )

Share

Related Charts:

Add Your Comments

Your email address will not be published. Required fields are marked *

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

A4 Medicine

Welcome to our newly updated website. A4Medicine is excited to announce that we continue to provide exceptional educational material to primary care healthcare professionals at an affordable rate. Please see our subscription plans for pricing. All plans come with a free 15-day trial. No money is taken from your payment method before the end of the free trial.

We are glad to offer all existing members/customers a 30% discount on yearly membership. If you have purchased The Visual Guidebook - you can claim the 30 % discount. These changes are applicable from 8th May 2021 and for any questions please write to contact@a4medicine.co.uk

Enjoy free 5 minutes browsing as a paid member

AN INVESTMENT IN KNOWLEDGE ALWAYS PAYS THE BEST INTEREST