Inherited renal tubular defect resulting in urinary
loss of magnesium, sodium, potassium, and chloride with otherwise normal
Primary Renotubular Hypomagnesemia-Hypokalemia with
Autosomal recessive; caused by mutation in the
thiazide-sensitive sodium-chloride cotransporter gene (SLC12A3 gene). More than 100
different mutations distributed throughout the whole protein have been
reported. Gene locus is 16q13.
Alteration of the thiazide-sensitive sodium
chloride transporter impairs sodium and chloride reabsorption and stimulates
renin and aldosterone secretion, resulting in hypokalemia and metabolic
alkalosis. Reasons for renal magnesium wastingare unknown.
Made by biochemical changes (alkalosis, hypokalemia,
hypomagnesemia, hypocalciuria). Although some features overlap with Bartter
syndrome, in contrast to Bartter syndrome, Gitelman syndrome patients
present later in life with hypomagnesemia, high fractional excretion of
magnesium, and low calcium excretion, but no overt hypovolemia.
Late childhood presentation with hypokalemic
metabolic alkalosis and hypomagnesemia. Either asymptomatic or occasional
mild episodes of muscle weakness. Symptoms are precipitated by nonspecific
illness and may consist of tetany. Patients are neither polyuric nor
polydipsic, but they have hypocalciuria, renal magnesium wasting, and
absence of nephrocalcinosis. Chronic dermatitis, skeletal problems with
growth retardation (as a consequence of rickets), and chondrocalcinosis;
rarely rhabdomyolysis (secondary to severe hypokalemia) can be observed in
some patients. Long-term prognosis is rather good, especially when potassium
losses are corrected. Treatmentwith oral magnesium corrects the
magnesium deficit but not themetabolic alkalosis. The relationship of
these skeletal abnormalities to magnesium wasting and hypomagnesemia is
Obtain history of frequency and
severity of tetany and muscle weakness as an indicator of disease severity.
Obtain electrolyte levels (potassium, magnesium, calcium) and arterial blood
gas analysis. Correct electrolyte abnormalities preoperatively.
The catecholamine stress response
associated with direct laryngoscopy and tracheal intubation further
exacerbates hypokalemia (intracellular entry). The arrhythmogenic potential
of hypokalemia is thought to result from electrical inhomogeneity,
alterations in conduction, changes in automaticity, and disturbances in
sodium pump kinetics. Hypomagnesemia favors atrial dysrhythmias. Use of a
nerve stimulator is mandatory if general anesthesia with muscle relaxants is
considered. Postanesthetic care should be in a high-dependency area for 24
to 48 hours or until the patient is stable with normal potassium and
magnesium levels. Should cardiac dysrhythmias occur, determination of serum
potassium, calcium, and magnesium concentrations are essential in guiding
Muscle relaxants (preferably
atracurium or cis-atracurium) can be used (under the monitoring of peripheral
nerve stimulator). Use of catecholamines and other vasoactive drugs may
exacerbate preexisting hypokalemia because of the intracellular shift of
potassium. Careful administration of glucose-based intravenous solution may
contribute to exaggeration of the hypokalemia.
Bartter Syndrome: Family of disorders characterized by
hypokalemic, hypochloremic, hypomagnesemic variants with hypocalciuria,
metabolic alkalosis, and normotensive hyperreninemic hyperaldosteronism
linked to the gene encoding the thiazide-sensitive Na/Cl-cotransporter
(TSC). The responsible gene here is located on chromosome 1p 36.
Gullner Syndrome: Findings differ from those ...