Hyperkalemic

Introduction:

The major features found in all the periodic paralyses are:

1. Attacks almost always begin before the age of 25, though occasionally later in life. ATS patients can develop first symptoms at any age.

2. Serum potassium fluctuates shortly before an attack, but serum potassium level will normalize before the attacks resolves and will be within the normal range between attacks. This is not a disorder of the blood but one in which there is an inappropriate shift of fluid, K+ and NA+ during attacks. 

When evaluating patients for periodic paralysis it is vital to obtain accurate results from blood draws. Because potassium levels which vary only a fraction of a point may be enough to trigger weakness in some patients, the lab may need to be made aware of specialized procedures which should ideally be used to obtain samples for K+ evaluation.

From "A Manual of Laboratory Diagnostic Tests" by Frances Fischbach, Page 247-253.

Potassium (K+) Normal Values: 3.5-5.0 mmol/liter 4.0-4.7 mmol/liter (average)

Clinical Signs

Hyperkalemic Periodic Paralysis is a genetically determined disorder which causes attacks of weakness and flaccid paralysis. Attacks last from 10 min to 1 hour, very rarely up to 1-2 days. Some patients experience only a few attacks over their lifetime, others have attacks every day. Diagnosis is suggested by attacks of weakness during which the patient's serum potassium is above 5.0 mmol/l or rises at least .5 of a mmol/l above their normal level when not in an attack.

Acetazolamide (aka Diamox) is frequently prescribed as therapy for the periodic paralyses. While most patients take this drug without incident it can interact with other drugs. Physicians should be aware of potential problems which might arise.

Patients with Sodium channel HyperKPP and PMC mutations are at increased risk of Malignant Hyperthermia;

Periodic Paralysis Patients at Increased Risk of MH

Patients with Hyperkalemic periodic paralysis and Paramyotonia Congenita are at increased risk for Malignant Hyperthermia (MH) during surgery. 

Giorgio Buzzi, MD, Neurologist

Buzzi G, Mostacci B, Sancisi E, Cirignotta F. Sleep complaints in Periodic Paralyses: a web survey. Functional Neurology 2001, 17 (3). From the Sleep Medicine Unit - Dept. of Neurology S.Orsola-Malpighi Hospital - University of Bologna, Italy.

SUMMARY

Section 1. Background: K+ and REM sleep homeostasis.

Section 2. The Periodic Paralysis International/HKPP Listserv Survey: results and discussion.

Hao Cheng, MD   

The use of local anaesthetics on patients with periodic paralysis presents some unusual challenges. Many patients report that these agents trigger weakness or paralysis, a phenomenon which is substantiated in medical literature. Some patients also report that the agents do not produce the desired anaesthesia.

In July of 1998 we conducted a survey of 64 self-reported clinically diagnosed periodic paralysis patients, all members of the HKPP Listserv. The questionnaire underwent no formal validation process, nor was the data assessed by personnel trained in this field. The patients surveyed were drawn from several countries and across several racial/ethnic lines and backgrounds.

The Compound Muscle Action Potential (CMAP)  test (aka the Exercise EMG) is now being used to diagnose the periodic paralyses. When done correctly this test is reported to positively identify 70%-80% of patients.