Calcium Flashcards

Question

What are causes of Hypocalcaemia?

Answer 1

* Hypothyroidism: Magnesium deficiency, Post-surgical damage or neck irradiation, Infiltrative (e.g haemachromatosis,wilson's disease and metastases), Genetic (DiGeorge syndrome) * Parathyroid hormone resistance: Pseudohypoparathyroidism * Abnormalities of vitamin D metabolism: Vitamin D deficiency * Deficient A1-hydroxylase enzyme activity: Chronic Kindey disease, Acidosis, Vitamin D-dependant rickets type 1 * Vitamin D resisitance: Vitamin D-dependant rickets type 1 * Others: Spurios, Acute Pancreatitis, Sepsis, Blood trnasfusion, Rhabdomyolysis, Bisphosphonate therapy, Hungry bone syndrome

Answer 2

* **Fall in calcium:** Decreased conversion 25(OH)D to 1,25(OH)2D * **Increase in phosphate:** Kidneys not excreting excess. FGF-23 has role in monitoring phsopahate * **Increase in PTH:** Stimulated by low calcium. Continual stimulation of parathyroid glands leads to secondary hyperparathyroidism * Patients with end stage renal failure can become hypercalcaemic. Probably due to development of autonomous PTH secretion from prolonged hypocalcaemic stimulus * Such hypercalcaemia may manifest for the first time in a renal transplant patient who becomes able to metabolise vitamin D normally leading to Tertiary hyperparathyroidism

Answer 3

* Resistance to PTH and various other glycoprotein hormones. * PTH resistance at the kidney so patients so hyperparathyroid bone disease

Answer 4

Involves measurement of **serum and urinary phosphate and cAMP** after intravenous administration of parathyroid extract; used in the diagnosis of pseudohypoparathyroidism. 6-30min urine collections and corresponding serum samples * Normally 10-12 fold increase in cAMP, fall in TmP/GFR of 20% * Pseudo type I: \<5-fold increase in cAMP, \<10% fall in TmP/GFR * Pseudo type II: normal response to cAMP, \<10% fall in TmP/GFR

Answer 5

* Paraesthesia * Circumoral numbness * Cramps * Anxiety * Tetany are followed by convulsions * Laryngeal stridor * Dystonia * Psychosis

Answer 6

* **Chvostek's sign:** Gentle tapping over the facial nerve causes twitching of the ipsilateral facial muscles * **Trousseau's sign:** Inflation of the sphygmomanometer cuff above systolic pressure for 3 minutes induces tetanic spasm of the fingers and wrist

Answer 7

* Prolongation of the QT-interval * Narrowing of the QRS complex * Reduced PR interval * T wave flattening and inversion * Prominent U-wave

Answer 8

Treat underlying condition * Acute symptomatic patient (10-20 mL 10 % calcium gluconate over 5 mins, Follow with continuous infusion of 9-18mmol/2L/24 h) * Magnesium replacement * Cholecalciferol (Vitamin D3) * Alfacalcidol (1-α hydroxylated vitamin D3) - Given when 1-αhydroxylation defective (1-4 µg/day) e.g. hypoparathyroidism, VDDR I * Calcitriol (1,25(OH)2 vitamin D3) - 0.75-2.25 µg/day

Answer 9

* Mild adjusted calcium \>2.60-\<3.0 mmol/L * Moderate adjusted calcium 3.0-3.5 mmol/L * Severe adjusted calcium \>3.5 mmol/L

Answer 10

* **Parathyroid hormone mediated:** Sporadic (adenoma, hyperplasia or carcinoma) , familial , Ectopic parathyroid hormone in malignancy, tertiary hyperparathyroidism * **Malignancy:** Humoral hypercalcaemia of malignancy, Local osteolysis, Ectopic parathyroid hormone in maignancy, calcitriol related hypercalcaemia * **Vitamin D related:** Granulomatous disease, Vitamin D intoxication * **Endocrine Disorders:** Thyrotoxicosis, Adrenal insufficiency, Pheochromacytoma, VIPoma (Verner-Morison) syndrome * **Drugs:** Thiazide diuretics, Lithium, Milk-Alkali syndrome, Vitmain A, Parathyroid Hormone * **Others:** Coexisting malignancy and primary hyperparathyroidism, immobilisation, Acute renal failure, Chronic renal failure treaed with calcium and calcitriol or vitamin D analogues, Renal Transplant

Answer 11

* **Primary:** One or more parathyroid glands secrete excess parathyroid hormone * **Secondary:** Increased secretion of this hormone is a response to lowered ionised calcium as a result of kidney, liver, or bowel disease * **Tertiary:** State of autonomous secretion of parathyroid hormone usually occurs as a result of longstanding chronic kidney disease

Answer 12

One or more of the four parathyroid glands secrete excess PTH, resulting in hypercalcaemia * Parathyroid gland adenoma * 1 gland: 80 % * 2-3 glands: 10-11 % * ≥4 glands \<10 % * Parathyroid carcinoma is rare (~1 %).

Answer 13

* Increased PTH * Long Hx of moderate hypercalcaemia * Development of nephrolithiasis * Plasma PO4 low in 50% cases * Hyperchloraemic metabolic acidosis * Normal ALP seen in 50% of cases Need to confirm Dx with clinical and radiological evidence

Answer 14

* Serum calcium 0.24 mmol/L above the upper limit of the normal range, for patients younger than 50 years of age * Men and peri-menopausal or postmenopausal women ≥50 years of age who have T scores of −2.5 or lower at a central bone densitometry site or in the distal third of the radius or who recently have had a fragility fracture * GFR \<60 mL/min/1.73 m2 * Renal stones, and a urine calcium level of \>400 mg per day (10.0 mmol per day)

Answer 15

* Erosion of bone by secondaries * Production of PTH like substance e.g. PTHrP * Prostaglandin produced by tumour * Production of osteoclast activating factor * Coincidence of hyperparathyroidism * Ectopic PTH

Answer 16

* Autosomal dominant * Patients are heterozygous for inactivating mutations in the calcium sensing receptor (CaSR) * Set point for PTH increased, mild PTH dependent hypercalcaemia develops with hypocalciuria * In FHH inappropriate avid reabsorption of Ca2+ * Largely asymptomatic (accounts for 2 %)

Answer 17

* Lethargy * Polydipsia * Pancreatitis Neonates with two mutations present with severe life threatening hypercalcaemia

Answer 18

**UCa/Cr Cl ratio** = **(U[Ca] (mmol/L) x P[Creat] (µmol/L)** / (**P[Ca] (mmol/L) x U[Creat] (mmol/L)** **Ca/Cr Cl ratio:** * \<0.01 in FHH * \>0.015 in PHP

Answer 19

* Tiredness * Malaise * Dehydration * Depression * Renal colic from stones * Polyuria or nocturia * Haematuria * Hypertension occurs * May have bone pain. Hyperparathyroidism mainly affects cortical bone * Bone cysts and locally destructive 'brown tumours' occur but only in advanced disease * Bone disease may be more apparent when there is coexisting vitamin D deficiency * Abdominal pain * Chondrocalcinosis and ectopic calcification (rare) * Corneal calcification (long-standing hypercalcaemia)

Answer 20

Hypercalcaemia speeds up repolarisation * **Mild:** Broad based tall peaking T waves * **Severe:** Extremely wide QRS, Low R wave, Disappearance of p waves, Tall peaking T waves.

Answer 21

Mandatory if the patient is seriously ill or if Ca2+ \>3.0 mmol/L * Rehydrate 4-6 L of 0.9 % saline on day 1, and 3-4 L for several days thereafter * IV bisphosphonates: Treatment of choice in malignancy and of undiagnosed cause. Zolendronate (4 mg) in 0.9 % saline and Pamidronate (60-90 mg) in 0.9 % saline * Prednisolone (30-60 mg daily): Used in granulomatous disease * Calcitonin (200 units i.v. 6-hourly, maximum use 5 days): Has short-lived action

Answer 22

* Ensure eGFR \>60 mL/min/1.73 m2 * [Ca2+] fall after 24-72 hours, lasting for approximately two weeks

Answer 23

* **Abdominal X-rays** may show renal calculi or nephrocalcinosis * **High-definition hand X-rays** can show sub-periosteal erosions in the middle or terminal phalanges * **DEXA bone density scan** is useful to detect bone effects in asymptomatic patients with HPT in whom conservative management is planned * **USS** which, though insensitive for small tumours, is simple and safe * **High-resolution CT scan or MRI** (more sensitive) * **Radioisotope scanning** using technetium (99mTc)sestamibi: 90 % sensitive in detecting adenomas

Calcium Flashcards

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