Electrolytes

Front 1

Calcium:
bound in bone as phosphate and carbonate, and remainder in ECF.

Primarily absorbed in small intestine
by ACTIVE (vit d dependent) and PASSIVE (concentration dependent) absorption.

Absorption is enhanced by vit D.

Excreted mainly in stool.

Serum Calcium is maintained by: PTH (parathyroid hormone)
vit D metabolites (D3, calcitriol)
Calcitonin

50% is bound to albumin
10% is complexed with serum ions
40% is free ionised state which is the physiologically active state - and is tightly regulated by endocrine system.

99% of filtered load of Ca is reabsorbed by kidneys

Approx 90% occurs in prox tubule, the other 10% is reabsorbed in distal tubule under the influence of PTH.

PTH also mediates the change of vit D to its active form (dihydroxy cholecalciferol)

The skeleton acts as a calcium pool that buffers acute changes in serum concentration.
When the serum calcium level falls, PTH stimulates an increase in bone turnover and the release of calcium into the serum.
A rise

Back 1

The serum calcium level reflects the net outcome of several processes:

On one hand, intestinal absorption and bone resorption add calcium to the blood;

on the other, calcium is lost from the blood by renal excretion, skeletal uptake, or abnormal deposition in soft tissues.

A decrease in the serum Ca2+ activates the PTH−vitamin D system to increase the entry of calcium into the blood from the bone and gastrointestinal tract.

A rise in the serum calcium level suppresses the PTH−vitamin D system and increases the release of calcitonin, which decreases calcium entry into the blood.

Front 2

90% of protein bound Ca is bound to albumin therefore changes in serum albumin will affect measured plasma Ca level. need to look at corrected Calcium.

Pseudohypercalcémie can be due to increased PROTEIN in serum - but protein bound Ca is not active component. Look for origin of increased protein.

Back 2

Clinical features of hypercalcemia:

nausées et vomissements
pert d'apétit
constipation
polyurie et polydipsie (et déshydratation si pas corrigé)
Dépression
état confusionnelle
Coma
seizures
muscle atonia
arrythmias (short QT)

Complications de hypercalcémie:
renal calculi
arrthymias (courte QT)
PUD
pancréatite

Front 3

Mechanisms of Hypercalcemie:

**Bone resorption (most common)
- primary hyperparathyroidism (usually caused by an adenoma) leading to increaesed PTH levels, increased serum Ca lvl and decreased Phosphate lvls.

* paraneoplastic -
Malignancies can produce agents that stimulate bone reabsorption eg parathyroid hormone related protein (PTHrP). Malignancy can also cause bone reabsorption by bony mets. Multiple myeloma.

* Increased GIT absorption of Ca - in lymphoma and granulomatous disease eg sarcoidosis (due to increased prod of 1-25hydroxy-vit-D

*Decreased renal excretion of Calcium - diuretics, lithium

Back 3

hypercalcemie:

severe > 3.5

NORM 2.2- 2.5

symptomatique normalement >3

ECG courte QT (<320ms)

Front 4

Etiologie hypercalcemie:

*Néoplasie
Metastases osseuse
Myélome multiple
Syndrome paranéoplasique
carcinomes - (bronches, ovaires, pancreas), Glucagonome (tumeur pancreatique, lymphome de hodgkins.

*Granulomatose, sarcoidose

*Endocrinopathies
- insufficance surrenalienne, hyperthyroidisme, pheochromocytome

* Medicamenteuse
-Diuretic thiazidique (en revanche diminues avec diuretiques de l'anse)
-Intoxication a la vit A ou D.
- Oestrogene, tamoxifene, lithium

Origine divrerse:
- Insufficance renale chronique (hyperparathyroidism tertiaire)
Immobilisation
Fausses resultat - hemolyse etc

Back 4

Treatment de hypercalcémie:

Traite la cause! puis -->

- hydratation
- diuretique de l'anse
- IV bispohosphonate (les bisphophonates colle a la surface osseuse et inhibitent resorption osseuse par les osteoclasts.) eg acide zoledronique et pamidronique

Autres:
coricosteroids

Front 5

Hyponatremia:

HYPOVOL: hyperosmalar
CHF
cirrhose
Nephrosis

EUVOLAEMIC

HYPERVOLEMIQUE

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Symptomes of hypernatremie et hyponatremie - CNS problems - SEIZURES!!

if rapidly corrected - causes CNS probs also

Severité - based on symptoms:
mild - no sx
severe - seizures

If mild - fluid restrict only

Front 6

Magnesium - dont do level or substitute unless K is low. if K low give K and Magnesium. otherwise dont substitute.

Back 6

Hyperkaliemie

Front 7

Effects secondaire de corticoide usage:
- candidose buccal/oesophagienne
- osteoporose
- augmentation d'apetit
- retention hydrosodée
- bos de bison
- fragilité de peau
- hyperglycemie

Back 7

Usage de corticoide a long terme - donne:
calcimagon 500mg 2x/j (calcium et vit D)

Front 8

abs for UTI:
1st choice femmes: nitrofurantoin
(uvamin)

Back 8

second choix: cephalexin rocephene)

Front 9

causes of Hyponatremie:

**Redistributive type
Hyperglycemia
Mannitol

***Hypovolemic type
Renal losses
Gastrointestinal
Third-space losses
Excessive sweating
Addison's disease

***Euvolemic type
SIADH
Psychogenic polydipsia

***Hypervolemic type
Congestive heart failure
Hepatic cirrhosis
Nephrotic syndrome

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